PartnerFacts
Data last updated: Oct 23, 2026, 5:45 PM ETLatest filing: Oct 22, 2026Now: Oct 24, 2026, 6:49 AM ET

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WK
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William Koster

Named as an officer, director or promoter on SEC Form D filings · MA · Jul 31, 2012 → Sep 14, 2018

2deals (issuers)
$35.8Mreported sold
139investors
9Form D filings
2012–2018years on file
Follow this personLook further ↓PDF

Data last updated Oct 23, 2026, 5:45 PM ET · Courts (RECAP) last checked: Oct 24, 2026, 2:26 AM ET · SEC enforcement last checked: covered by the index scan as of Oct 24, 2026, 2:50 AM ET

The short version

William Koster is listed as a director on 9 SEC Form D filings by 2 issuers between Jul 2012 and Sep 2018: Elicio Therapeutics, Inc. (Boston, MA — biotechnology — 2016–2018; $25.8M reported sold to 137 investors) and eXIthera Pharmaceuticals, Inc. (Westborough, MA — biotechnology — 2012–2017; $10M reported sold to 2 investors).

What this means 2 separate companies raised money with this person listed as director, over about 6 years. Across those companies the filings report $35.8M sold in total.

Listed alongside Isaac Kohlberg (6 shared filings), Frans Stassen (5 shared filings), Neil J. Hayward (5 shared filings), Daniel Geffken (3 shared filings), Frank Haluska (3 shared filings) and 9 others.

What this means These are the other officers, directors or promoters the companies named on the same forms — the team around William. Each name links to their own page.

1 of the issuers belongs to the sponsor group Elicio Therapeutics (2 issuers, $28M reported sold, 2012–2024).

What this means A sponsor group is one team that sets up a new company for each deal. Elicio Therapeutics has 2 companies on file and $28M reported sold in total — the group page shows the whole track record in one place.

Public records searched: federal courts (CourtListener / RECAP), SEC enforcement releases, state securities regulators (AR, AZ, CA, CT, DE, FINRA, GA, HI, ID, LA, ME, MO, MS, MT, NASAA, NC, NH, NM, OR, RI, TX, WA) — 9 bankruptcy cases matching the name listed in Key records below.

What this means 9 records came back. Each one is listed below with a link to the original document and a line saying why it matched. A name match is not proof it is the same person or company — read the why line and the document. Being sued or named in a release is an accusation, not a finding.

We compared 9 public filings for William Koster and found 5 differences: 5 offerings have no amendment in the last 12 months and may still be open; Offering amount changed between filings; and more below.

What this means These are differences between the sponsor's own SEC filings — both values, dates and sources are listed in Key records, section 4. Most have ordinary explanations; ask the sponsor.

What the community is saying

Community search for William Koster has not run yet — it is joining a line of 20,334 names; searches run around the clock at the hosts' allowed rate. Searched so far: 299 names.

Community comments are quoted as written by their authors. Sources searched: BiggerPockets forums (via DuckDuckGo, Brave, Bing and BiggerPockets search) and Reddit (search feed + public archive).

Key records

Five things investors ask first. Items still in human review are counted, not shown.

1. Lawsuits

None found in sources searched — federal courts (CourtListener / RECAP), checked Oct 24, 2026

What was searched

Sources searched: CourtListener bulk data (RECAP dockets as of 2026-09-30; recall-first rule 10-24) — federal district + bankruptcy courts State courts: not covered (one-tap state court links under Look further). PACER: not searched. · Last checked Oct 24, 2026, 2:26 AM ET.

State courts: not covered (one-tap state court links under Look further). No state offers a lawful automated statewide source PartnerFacts can use today. Texas (re:SearchTX) terms prohibit storing results in a database open to third parties; New York (WebCivil) and Massachusetts (MassCourts) require a browser check that blocks scripted queries; California has no statewide index (58 county portals; Rule of Court 2.503 grants name-based access case by case); Florida, Utah and Illinois offer paid or partial access whose terms for automated use are unverified. Washington (dw.courts.wa.gov; bulk index reports under a JISC data-dissemination agreement), Delaware (CourtConnect; Court of Chancery not included) and Arizona (apps.azcourts.gov/publicaccess, which has an official channel to request high-volume access) are the candidates; PartnerFacts will request written permission before any automated search. Federal courts are searched through CourtListener / RECAP.

2. Regulatory actions

None found in sources searched — SEC enforcement releases (index scan as of Oct 24, 2026, 2:50 AM ET) · state securities regulators: NV (crawled Oct 23, 2026)

What was searched

SEC enforcement searched: SEC litigation releases and administrative proceedings — respondent names in the sec.gov index titles (30,205 releases, 1995-09-19 to 2026-10-23); release text is read only to confirm a candidate. Names that appear only in the body of a release are not found. — Searched SEC litigation releases and administrative proceedings (1995→ / 2007→) (30,205 records as of Oct 24, 2026, 2:50 AM ET) — nothing matched William Koster..

State securities regulators: Securities regulators searched (3,318 actions): AZ Corporation Commission Securities Division (411 actions, 2017–2026), CA DFPI (25 actions, 2007–2024; listing starts 2002), DE DOJ Investor Protection Unit (257 actions, 1987–2026), TX State Securities Board (586 actions, 2006–2026), WA DFI (2,039 actions, 2001–2026) — 16 of 12,159 DFPI respondent pages read so far; sponsor-name matches are read first — last crawled Oct 23, 2026, 9:57 PM ET. No machine-readable public listing today for IA, IN, KS, MI, NE, NV (see docs/state-regulators.md).

3. Bankruptcies

9 cases: 9 closed (disposition not in docket feed)

William Koster, IV and Leticia Marie Koster closed
United States Bankruptcy Court, W.D. Pennsylvania · No. 20-20156 · Filed Jan 15, 2020 · Closed May 13, 2020
Role of William Koster, IV: Debtor · Outcome: Case closed 2020-05-13 (disposition not included in the bulk docket feed — see docket) Docket on CourtListener ↗
same full name (a name found in 12 federal dockets); 3 people with this name in Form D filings; court in PA (not a filing state)
William Koster closed
United States Bankruptcy Court, E.D. New York · No. 8-17-70273 · Filed Jan 17, 2017 · Closed Mar 3, 2017
Role of William Koster: Debtor · Outcome: Case closed 2017-03-03 (disposition not included in the bulk docket feed — see docket) Docket on CourtListener ↗
same full name (a name found in 12 federal dockets); 3 people with this name in Form D filings; court in NY (not a filing state)
William Koster closed
United States Bankruptcy Court, E.D. New York · No. 8-16-75210 · Filed Nov 9, 2016 · Closed Dec 21, 2016
Role of William Koster: Debtor · Outcome: Case closed 2016-12-21 (disposition not included in the bulk docket feed — see docket) Docket on CourtListener ↗
same full name (a name found in 12 federal dockets); 3 people with this name in Form D filings; court in NY (not a filing state)
William C. Koster closed
United States Bankruptcy Court, E.D. New York · No. 8-08-73682 · Filed Jul 10, 2008 · Closed Oct 17, 2008
Role of William C. Koster: Debtor · Outcome: Case closed 2008-10-17 (disposition not included in the bulk docket feed — see docket) Docket on CourtListener ↗
same full name (a name found in 12 federal dockets); 3 people with this name in Form D filings; court in NY (not a filing state)
William T Koster closed
United States Bankruptcy Court, N.D. Alabama · No. 08-70828 · Filed Apr 29, 2008 · Closed Oct 28, 2011
Role of William T Koster: Debtor · Outcome: Case closed 2011-10-28 (disposition not included in the bulk docket feed — see docket) Docket on CourtListener ↗
same full name (a name found in 12 federal dockets); 3 people with this name in Form D filings; court in AL (not a filing state)
William Koster closed
United States Bankruptcy Court, D. New Jersey · No. 03-27630 · Filed May 23, 2003 · Closed Nov 24, 2003
Role of William Koster: Debtor · Outcome: Case closed 2003-11-24 (disposition not included in the bulk docket feed — see docket) Docket on CourtListener ↗
same full name (a name found in 12 federal dockets); 3 people with this name in Form D filings; court in NJ (not a filing state)
WILLIAM F. KOSTER and CHUT T. KOSTER closed
United States Bankruptcy Court, D. Nevada · No. 99-11982 · Filed Mar 12, 1999 · Closed Jan 18, 2007
Role of WILLIAM F. KOSTER and CHUT T. KOSTER: Debtor · Outcome: Case closed 2007-01-18 (disposition not included in the bulk docket feed — see docket) Docket on CourtListener ↗
same full name (a name found in 12 federal dockets); 3 people with this name in Form D filings; court in NV (not a filing state)
William P. Koster and Kimberly Ann Koster closed
United States Bankruptcy Court, N.D. Iowa · No. 96-22677 · Filed Oct 21, 1996 · Closed Mar 26, 1997
Role of William P. Koster and Kimberly Ann Koster: Debtor · Outcome: Case closed 1997-03-26 (disposition not included in the bulk docket feed — see docket) Docket on CourtListener ↗
same full name (a name found in 12 federal dockets); 3 people with this name in Form D filings; court in IA (not a filing state)
William Koster closed
United States Bankruptcy Court, D. New Jersey · No. 90-31140 · Filed Mar 20, 1990 · Closed Feb 21, 1991
Role of William Koster: Debtor · Outcome: Case closed 1991-02-21 (disposition not included in the bulk docket feed — see docket) Docket on CourtListener ↗
same full name (a name found in 12 federal dockets); 3 people with this name in Form D filings; court in NJ (not a filing state)
What was searched

Sources searched: Federal bankruptcy courts via CourtListener / RECAP archive (federal district courts, federal bankruptcy courts). State courts: not covered (one-tap state court links under Look further). PACER: not searched (RECAP only). · Last checked Oct 24, 2026, 2:26 AM ET.

Court records show docket facts only; we never restate allegations as facts. Outcome wording comes from the docket feed; where it does not state a disposition we say so.

State courts: not covered (one-tap state court links under Look further). No state offers a lawful automated statewide source PartnerFacts can use today. Texas (re:SearchTX) terms prohibit storing results in a database open to third parties; New York (WebCivil) and Massachusetts (MassCourts) require a browser check that blocks scripted queries; California has no statewide index (58 county portals; Rule of Court 2.503 grants name-based access case by case); Florida, Utah and Illinois offer paid or partial access whose terms for automated use are unverified. Washington (dw.courts.wa.gov; bulk index reports under a JISC data-dissemination agreement), Delaware (CourtConnect; Court of Chancery not included) and Arizona (apps.azcourts.gov/publicaccess, which has an official channel to request high-volume access) are the candidates; PartnerFacts will request written permission before any automated search. Federal courts are searched through CourtListener / RECAP.

4. Differences between public sources

Comparisons cover issuers and sponsor groups — see the issuer pages under Deals

5 differences found between the filings for William Koster (compared 9 filings on Oct 24, 2026)

Note · Jul 17, 2012 – Sep 14, 2018

5 offerings have no amendment in the last 12 months and may still be open

No amendment in the last 12 months on an offering that may still be open — Elicio Therapeutics, Inc. (latest filing Sep 14, 2018) · No amendment in the last 12 months on an offering that may still be open — Elicio Therapeutics, Inc. (latest filing Jun 5, 2018) · No amendment in the last 12 months on an offering that may still be open — eXIthera Pharmaceuticals, Inc. (latest filing Aug 25, 2017) · No amendment in the last 12 months on an offering that may still be open — Elicio Therapeutics, Inc. (latest filing May 24, 2016) · No amendment in the last 12 months on an offering that may still be open — eXIthera Pharmaceuticals, Inc. (latest filing Aug 13, 2012)

What this means SEC rules expect a yearly amendment while an offering is still going. Ask the sponsor which of these raises have closed.

Form D · Sep 14, 2018 ↗Elicio Therapeutics, Inc. — PartnerFacts page ↗Form D · Jun 5, 2018 ↗Form D · Aug 25, 2017 ↗
Sources
Note · Aug 15, 2014 – May 16, 2016

Offering amount changed between filings — eXIthera Pharmaceuticals, Inc.

The Aug 15, 2014 filing says $9,000,000 offered; the May 16, 2016 Form D/A says $10,000,000.

What this means The target raise changed. Raising the cap is common when a deal grows; ask whether the extra money has the same terms and use.

Form D (earlier) · Aug 15, 2014 ↗Form D/A (later) · May 16, 2016 ↗eXIthera Pharmaceuticals, Inc. — PartnerFacts page ↗
Sources
Note · Jul 31, 2012 – Aug 13, 2012

Offering amount changed between filings — eXIthera Pharmaceuticals, Inc.

The Jul 31, 2012 filing says $2,000,000 offered; the Aug 13, 2012 Form D/A says $4,000,000.

What this means The target raise changed. Raising the cap is common when a deal grows; ask whether the extra money has the same terms and use.

Form D (earlier) · Jul 31, 2012 ↗Form D/A (later) · Aug 13, 2012 ↗eXIthera Pharmaceuticals, Inc. — PartnerFacts page ↗
Sources
Note · Jul 31, 2012 – Aug 15, 2014

Industry group changed between filings — eXIthera Pharmaceuticals, Inc.

"Pharmaceuticals" (Jul 31, 2012 to Aug 13, 2012); then "Biotechnology" (Aug 15, 2014 to Aug 25, 2017).

What this means The issuer described its business differently on different forms. Often it is just a different box ticked; sometimes the deal itself changed. Ask which business your money is in.

Form D · Jul 31, 2012 ↗Form D · Aug 15, 2014 ↗eXIthera Pharmaceuticals, Inc. — PartnerFacts page ↗
Sources
Note · Jul 3, 2013 – Feb 4, 2015

Same name, different state: "William Koster" (RI) is a separate record

This page covers filings where the address state is MA. A separate record, "William Koster" with address state RI, is listed on 2 filings — most recently by Mnemosyne Pharmaceuticals Inc (Feb 4, 2015). Both records have filings in the same period (Jul 3, 2013 to Feb 4, 2015).

What this means Two records with one name were active at the same time. That can be one person listing different company addresses, or two different people. We keep them apart until a filing ties them together. Check both pages before you decide.

William Koster (RI) — PartnerFacts page ↗Form D/A · Feb 4, 2015 ↗Mnemosyne Pharmaceuticals Inc — PartnerFacts page ↗William Koster (MA) — this page ↗
Sources
What is compared

What is compared: every Form D and D/A we hold for this subject, side by side — filing dates vs. first-sale dates (the 15-day rule), amendment timing on open offerings (the yearly-amendment expectation), amounts sold, investor counts, offering amounts and minimums across amendments, industry and size bands, addresses, how each person's name and role is written, paid sellers' CRD numbers, and (for groups) where the member companies were formed and sit. Everything is as filed by the issuer; the SEC does not check it. Differences are common and usually have ordinary explanations — we show both values, the dates, and the source so you can ask. As of Oct 24, 2026.

5. Money to insiders

3 of 7 offerings report sales commissions totalling $2,273,250; 0 report finder's fees; 0 report proceeds to related persons. (includes amounts the issuer reported as estimates)

Offering (latest filing)Sales commissionsFinder's feesTo insidersPaid to sell itSource
Sep 14, 2018 D
Elicio Therapeutics, Inc.
File 021-321450
$525,000 (est.)$0$0None no CRD number reported
via Maxim Merchant Capital (CRD 120708 ↗)
EDGAR ↗
Aug 3, 2018 D
Elicio Therapeutics, Inc.
File 021-318453
$1,449,250 (est.)$0$0None no CRD number reported
via Maxim Merchant Capital (CRD 120708 ↗)
EDGAR ↗
Jun 5, 2018 D
Elicio Therapeutics, Inc.
File 021-313861
$299,000 (est.)$0$0None no CRD number reported
via Maxim Merchant Capital (CRD 120708 ↗)
EDGAR ↗
Aug 25, 2017 D
eXIthera Pharmaceuticals, Inc.
File 021-293500
$0$0$0None listed on this filingEDGAR ↗
May 24, 2016 D
Elicio Therapeutics, Inc.
File 021-263723
$0$0$0None listed on this filingEDGAR ↗
May 16, 2016 D/A
eXIthera Pharmaceuticals, Inc.
File 021-223015
$0$0$0None listed on this filingEDGAR ↗
Aug 13, 2012 D/A
eXIthera Pharmaceuticals, Inc.
File 021-182050
$0$0$0None listed on this filingEDGAR ↗
How this is counted

Counts come from Form D Items 12–15 on the filings in our index (latest filing per offering; one offering = one SEC file number; an amendment updates its offering rather than adding one). "To insiders" = gross proceeds used for payments to executive officers, directors or promoters. "—" = not reported on that filing. Amounts marked (est.) were reported as estimates. "Paid to sell it" = sales compensation recipients named on that filing (Item 12), each linked to FINRA BrokerCheck when a CRD number is reported.

Counted across every filing this person is listed on (latest filing per offering, per issuer).

Deals 2

Every issuer that named William Koster on a Form D, newest first. A Form D is the notice a company files after it starts selling a private investment.

ET
Biotechnology · group: Elicio Therapeutics

Elicio Therapeutics, Inc.

Boston, MA · May 24, 2016 → Sep 14, 2018 · 4 filings
  • Sep 14, 2018 · D · $25,817,848 sold of $36,235,347 · 137 investors · min. No minimum reported · role: Director EDGAR ↗
  • Aug 3, 2018 · D · $14,492,501 sold of $14,492,501 · 115 investors · min. No minimum reported · role: Director EDGAR ↗
  • Jun 5, 2018 · D · $2,990,000 sold of $3,000,000 · 27 investors · min. No minimum reported · role: Director EDGAR ↗
  • May 24, 2016 · D · $750,000 sold of $1,500,000 · 1 investors · min. No minimum reported · role: Director EDGAR ↗

Raised $25.8M from 137 investors (71% of the $36.2M target) as of the latest filing. William is listed as director on 4 filings for this deal.

Latest filing on EDGAR ↗
Sources

Every row is a Form D or D/A on which the issuer listed this name as a related person. Amount sold and investors are the maximum reported on any filing for this issuer. "Similar" = offerings in the same industry claiming the same exemption, filed in the last 5 years: Biotechnology / 506(b) (3,253 filings); ranges are the middle half (25th–75th percentile). Computed by PartnerFacts from SEC EDGAR Form D data as of Oct 23, 2026, 5:45 PM ET. Rows without a range: fewer than 30 comparable filings, or not a Rule 506 offering. No ranking or score.

EP
Biotechnology

eXIthera Pharmaceuticals, Inc.

Westborough, MA · Jul 31, 2012 → Aug 25, 2017 · 5 filings
  • Aug 25, 2017 · D · $3,000,000 sold of $5,400,000 · 2 investors · min. No minimum reported · role: Director EDGAR ↗
  • May 16, 2016 · D/A · $10,000,000 sold of $10,000,000 · 2 investors · min. No minimum reported · role: Director EDGAR ↗
  • Aug 15, 2014 · D · $6,000,000 sold of $9,000,000 · 2 investors · min. No minimum reported · role: Director EDGAR ↗
  • Aug 13, 2012 · D/A · $2,000,000 sold of $4,000,000 · 1 investors · min. No minimum reported · role: Director EDGAR ↗
  • Jul 31, 2012 · D · $2,000,000 sold of $2,000,000 · 1 investors · min. No minimum reported · role: Director EDGAR ↗

Raised $10M from 2 investors (100% of the $5.4M target) as of the latest filing. William is listed as director on 5 filings for this deal.

Latest filing on EDGAR ↗
Sources

Every row is a Form D or D/A on which the issuer listed this name as a related person. Amount sold and investors are the maximum reported on any filing for this issuer. "Similar" = offerings in the same industry claiming the same exemption, filed in the last 5 years: Biotechnology / 506(b) (3,253 filings); ranges are the middle half (25th–75th percentile). Computed by PartnerFacts from SEC EDGAR Form D data as of Oct 23, 2026, 5:45 PM ET. Rows without a range: fewer than 30 comparable filings, or not a Rule 506 offering. No ranking or score.

Other pages with the same name (2)

Separate person records under the same name, not combined with this page. Each line says whether it shares an issuer with this record.

  • William Koster — RI, 1 issuer, Jul 3, 2013 → Feb 4, 2015 · no shared issuer
  • William H. Koster — MA, 1 issuer, Sep 26, 2019 → Feb 22, 2024 · no shared issuer

People around William 14

Officers, directors, promoters and management entities named on the same filings, as of Oct 23, 2026, 5:45 PM ET.

IK
No photo found yet (own website and image search run after this page is viewed)
Person

Isaac Kohlberg

Director · 6 shared filings (2 issuers)

Listed on the same filings as William Koster. Their page shows their other deals.

FS
No photo found yet (own website and image search run after this page is viewed)
Person

Frans Stassen

Director · 5 shared filings (1 issuer)

Listed on the same filings as William Koster. Their page shows their other deals.

NH
No photo found yet (own website and image search run after this page is viewed)
Person

Neil J. Hayward

Director, Executive Officer · 5 shared filings (1 issuer)

Listed on the same filings as William Koster. Their page shows their other deals.

FM
No photo found yet (own website and image search run after this page is viewed)
Person

Fred Meyer

Director · 3 shared filings (1 issuer) · also on 1 other issuer

Listed on the same filings as William Koster. Their page shows their other deals.

IB
No photo found yet (own website and image search run after this page is viewed)
Person

Isaac Blech

Director · 3 shared filings (1 issuer) · also on 19 other issuers

Isaac Blech is on 20 issuers in total — a repeat sponsor. Their page lists every one.

JA
No photo found yet (own website and image search run after this page is viewed)
Person

Julian Adams

Director · 3 shared filings (1 issuer) · also on 2 other issuers

Listed on the same filings as William Koster. Their page shows their other deals.

SY
No photo found yet (own website and image search run after this page is viewed)
Person

Scott Yaphe

Director · 3 shared filings (1 issuer) · also on 2 other issuers

Listed on the same filings as William Koster. Their page shows their other deals.

DG
No photo found yet (own website and image search run after this page is viewed)
Person

Daniel Geffken

Executive Officer, Director · 3 shared filings (1 issuer) · also on 3 other issuers

Listed on the same filings as William Koster. Their page shows their other deals.

SJ
No photo found yet (own website and image search run after this page is viewed)
Person

Satish Jindal

Director · 3 shared filings (1 issuer) · also on 1 other issuer

Listed on the same filings as William Koster. Their page shows their other deals.

FH
No photo found yet (own website and image search run after this page is viewed)
Person

Frank Haluska

Director · 3 shared filings (1 issuer)

Listed on the same filings as William Koster. Their page shows their other deals.

DB
No photo found yet (own website and image search run after this page is viewed)
Person

Daniel Behr

Director · 2 shared filings (1 issuer) · also on 2 other issuers

Listed on the same filings as William Koster. Their page shows their other deals.

BB
No photo found yet (own website and image search run after this page is viewed)
Person

Ben Bronstein

Director · 2 shared filings (1 issuer) · also on 2 other issuers

Listed on the same filings as William Koster. Their page shows their other deals.

SD
No photo found yet (own website and image search run after this page is viewed)
Person

Steve Deitcher

Director · 1 shared filing (1 issuer)

Listed on the same filings as William Koster. Their page shows their other deals.

DG
No photo found yet (own website and image search run after this page is viewed)
Person

Dennis Goldberg

Director · 1 shared filing (1 issuer)

Listed on the same filings as William Koster. Their page shows their other deals.

The team behind the deals

ET
Sponsor group

Elicio Therapeutics

2 issuers · 21 filings · $28M reported sold · 2012–2024

One team, 2 deal companies. William Koster is listed on 1 of them.

Sources

Issuers are grouped when their Form D filings share related persons, a management entity or a business address (automatic match from the filings). "Listed" marks the issuers that name William Koster.

Same business address

2 other issuers file from the same address

A shared address can mean the same team, a shared office building or a registered agent. It is a lead, not a conclusion.

Registrations and other filings

Adviser registration (Form ADV)

None of the 2 issuers this person is listed on appears in Form ADV (searched 24,962 advisers as of Oct 2, 2026). A person is never an adviser firm; Form ADV is checked for the issuers and the management companies they are listed with.

Other offering types (Regulation A and Regulation Crowdfunding)

Searched SEC Regulation A Data Sets (Forms 1-A, 1-K, 1-Z; 2015 Q2 → 2026 Q3); SEC Crowdfunding Offerings Data Sets (Form C family; 2016 Q2 → 2026 Q3); EDGAR form index for 2026 Q3 → 2026 Q4 (51,358 records as of Oct 23, 2026, 8:41 PM ET) — nothing matched this name.

Property records none — individuals are not matched

Property records are matched to companies only, never to individuals, so none are matched to William Koster by design. Searched property records in Hillsborough County FL (Clerk recorded-document index Oct 14, 2026 to Oct 15, 2026 + FL DOR 2026 ownership roll), Miami-Dade County FL (FL DOR 2026 ownership roll), Harris County TX (HCAD 2026 ownership roll), Dallas County TX (DCAD 2026 ownership roll), New York City ACRIS documents and PLUTO ownership rows already retrieved for other issuers, Cook County IL sale and ownership rows already retrieved for other issuers (814,874 records as of Oct 23, 2026, 8:59 PM ET) for the 2 issuers this person is listed on — nothing matched.

Public profiles and social

Websites and social links of the issuers William Koster is listed on: none on file. No website or social profile named in eXIthera Pharmaceuticals, Inc.'s SEC filings (Form C, Reg A, Form ADV; checked Oct 24, 2026). Web search for this name: #267,481 of 374,652 in line (452 issuers searched so far). One-tap searches: Look further ↓

Look further

One-tap searches on sites we do not index ourselves, with the name pre-filled (Westborough, MA). Each opens in a new tab; what you find there is not verified by PartnerFacts.

Social and web

LinkedIn people search ↗Instagram ↗X (Twitter) ↗Facebook ↗YouTube ↗Google ↗Google Images ↗Google News ↗Meta Ad Library ↗

Courts

CourtListener / RECAP (federal) ↗PACER case locator (federal, login) ↗Massachusetts MassCourts ↗

Securities regulators

SEC EDGAR full-text search ↗SEC action look-up ↗FINRA BrokerCheck ↗SEC IAPD adviser search ↗

Business registries

Massachusetts Secretary of State business search ↗OpenCorporates ↗

Change history

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