Company · Ownership research

Upstream Bio, Inc. UPB

CIK 0002022626 · CUSIP 91678A107

Insider trading Initial holdings Institutional holders

Quarter-end disclosures, not live holdings.

Several CUSIPs are reported for this company; this page shows CUSIP 91678A107 (UPB), not CUSIP 91678A907 (UPB), CUSIP 91678A957 (UPB), and does not merge CUSIPs.

This page lists the top 20 of 38 rows by value; the complete set is available through the API.

Top 20 institutions

Weight means this stock's share of the manager's own portfolio.

By reported value

#	Manager	Value	Manager weight	Change vs prior	Source
01	GEODE CAPITAL MANAGEMENT, LLC CIK 1214717 · View history	$5.13M 972,580 shares	0.00%	+41.32K(+4.40%)Added	SEC filing ↗ Nov 6, 2026	▾
02	SEB Asset Management AB CIK 2127509 · View history	$4.63M 878,473 shares	0.02%	0(0.00%)Unchanged	SEC filing ↗ Nov 4, 2026	▾
03	Y-Intercept (Hong Kong) Ltd CIK 1772875 · View history	$3.39M 642,574 shares	0.07%	-50.98K(-7.40%)Reduced	SEC filing ↗ Oct 16, 2026	▾
04	DIMENSIONAL FUND ADVISORS LP CIK 354204 · View history	$1.97M 374,836 shares	0.00%	-6.78K(-1.80%)Reduced	SEC filing ↗ Nov 4, 2026	▾
05	BARCLAYS PLC CIK 312069 · View history	$1.04M 198,213 shares	0.00%	+169.00K(+578.60%)Added	SEC filing ↗ Nov 6, 2026	▾
06	Bank of New York Mellon Corp CIK 1390777 · View history	$511.97K 97,148 shares	0.00%	+11.40K(+13.30%)Added	SEC filing ↗ Nov 5, 2026	▾
07	ALPS ADVISORS INC CIK 1376113 · View history	$379.68K 72,045 shares	0.00%	+16.82K(+30.50%)Added	SEC filing ↗ Nov 3, 2026	▾
08	Simplify Asset Management Inc. CIK 1846368 · View history	$327.34K 62,113 shares	0.01%	0(0.00%)Unchanged	SEC filing ↗ Oct 27, 2026	▾
09	Russell Investments Group, Ltd. CIK 1692234 · View history	$253.64K 48,130 shares	0.00%	+587(+1.20%)Added	SEC filing ↗ Nov 6, 2026	▾
10	Allspring Global Investments Holdings, LLC CIK 1890906 · View history	$236.87K 44,947 shares	0.00%	+1.76K(+4.10%)Added	SEC filing ↗ Nov 4, 2026	▾
11	CITIGROUP INC CIK 831001 · View history	$188.31K 35,733 shares	0.00%	-4.61K(-11.40%)Reduced	SEC filing ↗ Nov 4, 2026	▾
12	STRS OHIO CIK 820478 · View history	$161.26K 30,600 shares	0.00%	+18.60K(+155.00%)Added	SEC filing ↗ Oct 30, 2026	▾
13	DEUTSCHE BANK AG\ CIK 948046 · View history	$152.26K 28,891 shares	0.00%	-212.56K(-88.00%)Reduced	SEC filing ↗ Nov 6, 2026	▾
14	Savant Capital, LLC CIK 1482880 · View history	$95.72K 18,164 shares	0.00%	+18.16KNew	SEC filing ↗ Nov 6, 2026	▾
15	Creative Planning CIK 1540235 · View history	$81.45K 15,456 shares	0.00%	-13.03K(-45.70%)Reduced	SEC filing ↗ Nov 2, 2026	▾
16	China Universal Asset Management Co., Ltd. CIK 1906594 · View history	$51.87K 9,994 shares	0.00%	+1.33K(+15.40%)Added	SEC filing ↗ Oct 28, 2026	▾
17	SIMPLEX TRADING, LLC CIK 1488542 · View history	$16.22K 3,078 shares	0.00%	+3.06K(+15,290.00%)Added	SEC filing ↗ Nov 4, 2026	▾
18	Parallel Advisors, LLC CIK 1690010 · View history	$16.07K 3,050 shares	0.00%	+3.05KNew	SEC filing ↗ Nov 3, 2026	▾
19	Mirae Asset Global Investments Co., Ltd. CIK 1569395 · Amended · View history	$14.75K 2,799 shares	0.00%	+365(+15.00%)Added	SEC filing ↗ Oct 29, 2026	▾
20	NISA INVESTMENT ADVISORS, LLC CIK 937615 · View history	$14.41K 2,734 shares	0.00%	-1.54K(-36.10%)Reduced	SEC filing ↗ Oct 20, 2026	▾

Showing 20 / 38 institutions. The complete set is available through the API.

Coverage & totals by quarter

Reporting institutions

Cancelled or null records excluded

Disclosed shares

3,550,437

Not deduplicated across managers

Disclosed value

$18.71M

Not market cap or free float

Reporting institutions by quarter

Counts also change with data coverage and reporting entities; they do not measure net buying. Distinct managers with a live stock row in this CUSIP; totals may include overlapping filings and are not a share of the company.

Upstream Bio, Inc. · Q3 2026

Explore all 38 reporting institutions.

This page includes 20 of 38 reporting institutions. Log in to look up the full history beyond 3 years, use advanced screening & filtering, download CSV, and get the complete set through the Akkru API.

Download CSV
Earlier quarters
Advanced screening & filtering
API & AI access

Already have an account?

＋ New accounts get free API credits to explore data beyond ownership filings.

For AI agents & developers

The initial HTML of this page carries its exact data as script#research-data (JSON): values, units, scope, preview limits and SEC sources. Read it directly, no script or API key needed; script#research-access says what needs an account. This page lists 20 of 38 reporting institutions; totals use the complete disclosed data.

Without an account: the last 3 years, with the row caps stated on the page. A free account opens all history on file on these pages and the CSV of what a page shows. Rows beyond the caps and bulk retrieval go through the authenticated API / MCP / CLI.

MCP  https://api.akkrudata.ai/mcp

akkru_institutional_holdings
{"action":"holders","cusip":"91678A107","quarter":"2026Q3","type":"positions","page_size":100}

Connect to MCP with OAuth and follow the returned pagination. Credits and usage limits depend on the account.

MCP endpoint: https://api.akkrudata.ai/mcp
API / MCP / CLI documentation: /documents
llms.txt: /llms.txt

Sources, coverage & how to read this data

Figures are as reported to the SEC and merged with later amendments where Akkru could match them. Preview limits apply to what is listed, not to the totals, which come from the complete reported data. Nothing is zero-filled: a missing quarter or month is shown as missing.