Vault-13

SERES THERAPEUTICS INC MCRB

COM NEW · Common Stock · CUSIP 81750R201

36 institutional holders +3 vs Q1 2026
2,274,3782.3m shares reported held*
22.9% of all shares outstanding*
$17.9mreported value*
8 new 7 added 12 reduced 5 sold out net sold ≈ $253.2k (-32.1k shares)

* Summed across managers. Shares that two managers' reports both contain – a subsidiary's holdings that its parent's report includes too, or a sub-adviser's in its client's – are counted once. Holder counts are more reliable. Shares outstanding: 9.9m as of 2026-08-03, from the company's own SEC filing; the percentage can still exceed 100%: lent-out shares are counted by the lender and the buyer, and some reports overlap without saying so. Implied quarter-end price ≈ $7.89. Options: 3 managers hold calls ($273.8k notional), 4 hold puts ($1.1m).

Trends to Q2 2026

Institutional holders

Managers reporting a position, each quarter

02040Q1 25: 4Q2 25: 33Q3 25: 32Q4 25: 36Q1 26: 33Q2 26: 3636Q1 25Q2 25Q3 25Q4 25Q1 26Q2 26
Numbers
QuarterHolders
Q1 20254
Q2 202533
Q3 202532
Q4 202536
Q1 202633
Q2 202636

Buyers vs sellers

Managers adding to or starting a position, vs cutting or selling out

Bought or addedCut or sold out
40040Q2 25: 32 bought or addedQ2 25: 4 cut or sold outQ2 25Q3 25: 20 bought or addedQ3 25: 17 cut or sold outQ3 25Q4 25: 22 bought or addedQ4 25: 12 cut or sold outQ4 25Q1 26: 12 bought or addedQ1 26: 15 cut or sold outQ1 26Q2 26: 15 bought or addedQ2 26: 17 cut or sold outQ2 26
Numbers
QuarterBought or addedCut or sold out
Q2 2025324
Q3 20252017
Q4 20252212
Q1 20261215
Q2 20261517

Calls vs puts

Options held, notional value, last 4 quarters. P/C = puts ÷ calls

CallsPuts
$0$5m$10m$15m$20mQ3 25 calls: $17.4mQ3 25 puts: $2.6mQ3 25P/C 0.15Q4 25 calls: $6.7mQ4 25 puts: $2.3mQ4 25P/C 0.35Q1 26 calls: $958.0kQ1 26 puts: $1.3mQ1 26P/C 1.41Q2 26 calls: $273.8kQ2 26 puts: $1.1mQ2 26P/C 3.88
Numbers
QuarterCallsPutsP/C
Q3 2025$17.4m$2.6m0.15
Q4 2025$6.7m$2.3m0.35
Q1 2026$958.0k$1.3m1.41
Q2 2026$273.8k$1.1m3.88

Biggest buyers

MARSHALL WACE, LLP Added +32,706+32.7k
XTX Topco Ltd New +20,732+20.7k
GOLDMAN SACHS GROUP INC New +15,229+15.2k
CITADEL ADVISORS LLC New +10,504+10.5k
VANGUARD FIDUCIARY TRUST CO Added +9,042+9.0k
BlackRock, Inc. Added +8,974+9.0k
GEODE CAPITAL MANAGEMENT, LLC Added +5,139+5.1k
Integrated Wealth Concepts LLC New +4,000+4.0k
JPMORGAN CHASE & CO New +3,636+3.6k
GROUP ONE TRADING LLC Added +2,890+2.9k

Biggest sellers

SUSQUEHANNA INTERNATIONAL GROUP, LLP Reduced -47,011-47.0k
AMERICAN CENTURY COMPANIES INC Reduced -34,003-34.0k
TWO SIGMA INVESTMENTS, LP Sold out -18,794-18.8k
Vontobel Holding Ltd. Reduced -15,493-15.5k
MORGAN STANLEY Reduced -9,562-9.6k
UBS Group AG Reduced -6,546-6.5k
VANGUARD CAPITAL MANAGEMENT LLC Reduced -6,367-6.4k
BARCLAYS PLC Reduced -6,340-6.3k
Invesco Ltd. Reduced -1,573-1.6k
CHARLES SCHWAB INVESTMENT MANAGEMENT INC Reduced -581-581

Biggest calls

SIMPLEX TRADING, LLC Added $131.0k16.6k shares
SUSQUEHANNA INTERNATIONAL GROUP, LLP Reduced $87.6k11.1k shares
GROUP ONE TRADING LLC Reduced $55.2k7.0k shares

Biggest puts

SUSQUEHANNA INTERNATIONAL GROUP, LLP Reduced $503.4k63.8k shares
CITADEL ADVISORS LLC Reduced $343.2k43.5k shares
GROUP ONE TRADING LLC Added $161.0k20.4k shares
SIMPLEX TRADING, LLC Reduced $54.4k6.9k shares

Options at notional value: the value of the shares the contracts control, as filers report them, not what the options cost. Not included in the holders, shares or buying above.

Insider purchases and sales since 1 Apr 2026

Shares bought or sold by the company's own officers, directors and 10% owners, in the open market or privately, as they reported to the SEC on Form 4 (due within two business days of the trade). Grants, option exercises, shares withheld for tax and gifts aren't included.

Officers and directors buying vs selling

Number of people, by quarter (10% owners not included)

BuyingSelling
505Q4 24: 0 buyingQ4 24: 5 sellingQ1 25: 0 buyingQ1 25: 5 sellingQ1 25Q2 25: 0 buyingQ2 25: 4 sellingQ3 25: 0 buyingQ3 25: 4 sellingQ3 25Q4 25: 0 buyingQ4 25: 4 sellingQ1 26: 0 buyingQ1 26: 4 sellingQ1 26Q2 26: 0 buyingQ2 26: 4 sellingQ3 26: 0 buyingQ3 26: 4 sellingQ3 26
Numbers
QuarterBuyingBoughtSellingSoldSold under a plan
Q4 20240—5$20.0k$20.0k
Q1 20250—5$23.3k$23.3k
Q2 20250—4$3.2k$3.2k
Q3 20250—4$7.1k$7.1k
Q4 20250—4$44.8k$44.8k
Q1 20260—4$4.2k$4.2k
Q2 20260—4$3.6k$3.1k
Q3 20260—4$2.2k$2.2k
DateInsiderTradeSharesPrice ValueTheir holding
2026-08-17 Shaff Eric D. Director Sold plan 263 $4.55 $1.2k263 shares -2%
2026-08-17 DesRosier Thomas Officer Sold plan 82 $4.55 $37382 shares -1%
2026-08-17 Henn Matthew R Officer Sold plan 81 $4.55 $36981 shares -1%
2026-08-17 Brady Kelly Officer Sold plan 64 $4.55 $29164 shares -1%
2026-05-18 Shaff Eric D. Director Sold plan 259 $7.53 $2.0k259 shares -2%
2026-05-18 DesRosier Thomas Officer Sold plan 79 $7.53 $59579 shares -1%
2026-05-18 Henn Matthew R Officer Sold plan 77 $7.53 $58077 shares -1%
2026-05-18 Brady Kelly Officer Sold 59 $7.53 $44459 shares -1%

Their holding: how much the trade added to or took from the insider's holding (direct, or the trust or fund named). The same trade is sometimes reported by more than one insider, such as a fund and the director who represents it; totals count it once. A value is left blank where the reported price is far from the market price (usually a typo).

Holders, Q2 2026

#ManagerLocationShares Value% of their portfolioChangeShares change
1 Flagship Pioneering, LLC 0.59% of their portfolio CAMBRIDGE, MA 1,155,8501.2m $9.1m $9.1m 0.59% Unchanged
2 VANGUARD CAPITAL MANAGEMENT LLC 0.00% of their portfolio MALVERN, PA 287,776287.8k $2.3m $2.3m 0.00% Reduced -6.4k -6,367
3 MARSHALL WACE, LLP 0.00% of their portfolio LONDON, X0 172,245172.2k $1.4m $1.4m 0.00% Added +32.7k +32,706
4 Vontobel Holding Ltd. 0.00% of their portfolio ZURICH, V8 122,975123.0k $970.3k $970.3k 0.00% Reduced -15.5k -15,493
5 BlackRock, Inc. 0.00% of their portfolio New York, NY 111,000111.0k $875.8k $875.8k 0.00% Added +9.0k +8,974
6 GEODE CAPITAL MANAGEMENT, LLC 0.00% of their portfolio BOSTON, MA 79,97480.0k $631.3k $631.3k 0.00% Added +5.1k +5,139
7 SUSQUEHANNA INTERNATIONAL GROUP, LLP 0.00% of their portfolio BALA CYNWYD, PA 58,32858.3k $460.2k $460.2k 0.00% Reduced -47.0k -47,011
8 VANGUARD FIDUCIARY TRUST CO 0.00% of their portfolio MALVERN, PA 48,68548.7k $384.1k $384.1k 0.00% Added +9.0k +9,042
9 STATE STREET CORP 0.00% of their portfolio BOSTON, MA 33,90133.9k $267.5k $267.5k 0.00% Unchanged
10 Lion Point Capital, LP 1.19% of their portfolio NEW YORK, NY 31,57031.6k $249.1k $249.1k 1.19% Unchanged
11 CHARLES SCHWAB INVESTMENT MANAGEMENT INC 0.00% of their portfolio SAN FRANCISCO, CA 31,04931.0k $245.0k $245.0k 0.00% Reduced -581 -581
12 AMERICAN CENTURY COMPANIES INC 0.00% of their portfolio KANSAS CITY, MO 28,31328.3k $223.4k $223.4k 0.00% Reduced -34.0k -34,003
13 XTX Topco Ltd 0.00% of their portfolio LONDON, X0 20,73220.7k $163.6k $163.6k 0.00% New
14 GOLDMAN SACHS GROUP INC 0.00% of their portfolio NEW YORK, NY 15,22915.2k $120.2k $120.2k 0.00% New
15 NORTHERN TRUST CORP 0.00% of their portfolio CHICAGO, IL 14,76514.8k $116.5k $116.5k 0.00% Unchanged
16 Invesco Ltd. 0.00% of their portfolio ATLANTA, GA 12,97413.0k $102.4k $102.4k 0.00% Reduced -1.6k -1,573
17 MORGAN STANLEY 0.00% of their portfolio NEW YORK, NY 12,13812.1k $95.8k $95.8k 0.00% Reduced -9.6k -9,562
18 CITADEL ADVISORS LLC 0.00% of their portfolio MIAMI, FL 10,50410.5k $82.9k $82.9k 0.00% New
19 SIMPLEX TRADING, LLC 0.00% of their portfolio CHICAGO, IL 4,5984.6k $36.3k $36.3k 0.00% Added +1.5k +1,528
20 SBI Securities Co., Ltd. 0.00% of their portfolio TOKYO, M0 4,1824.2k $33.0k $33.0k 0.00% Added +700 +700
21 Integrated Wealth Concepts LLC 0.00% of their portfolio WALTHAM, MA 4,0004.0k $31.6k $31.6k 0.00% New
22 GROUP ONE TRADING LLC 0.00% of their portfolio CHICAGO, IL 3,7143.7k $29.3k $29.3k 0.00% Added +2.9k +2,890
23 JPMORGAN CHASE & CO 0.00% of their portfolio NEW YORK, NY 3,6363.6k $28.3k $28.3k 0.00% New
24 Vanguard Global Advisers, LLC 0.00% of their portfolio MALVERN, PA 1,9752.0k $15.6k $15.6k 0.00% Unchanged
25 FMR LLC 0.00% of their portfolio BOSTON, MA 1,5281.5k $12.1k $12.1k 0.00% Reduced -224 -224
26 Rachor Investment Advisory Services, LLC 0.01% of their portfolio Linden, MI 1,4771.5k $11.7k $11.7k 0.01% Unchanged
27 UBS Group AG 0.00% of their portfolio ZURICH, V8 484484 $3.8k $3.8k 0.00% Reduced -6.5k -6,546
28 Tower Research Capital LLC (TRC) 0.00% of their portfolio NEW YORK, NY 316316 $2.5k $2.5k 0.00% Reduced -478 -478
29 BNP PARIBAS FINANCIAL MARKETS 0.00% of their portfolio PARIS, I0 211211 $1.7k $1.7k 0.00% Unchanged
30 BARCLAYS PLC 0.00% of their portfolio LONDON, X0 167167 $1.3k $1.3k 0.00% Reduced -6.3k -6,340
31 Continuum Advisory, LLC 0.00% of their portfolio EAGLE, ID 4747 $371 $371 0.00% New
32 ROYAL BANK OF CANADA 0.00% of their portfolio TORONTO, A6 1111 $0 $0 0.00% Reduced -96 -96
33 WELLS FARGO & COMPANY/MN 0.00% of their portfolio SAN FRANCISCO, CA 1010 $79 $79 0.00% Unchanged
34 OSAIC HOLDINGS, INC. 0.00% of their portfolio SCOTTSDALE, AZ 88 $63 $63 0.00% Unchanged
35 Larson Financial Group LLC 0.00% of their portfolio ST LOUIS, MO 55 $39 $39 0.00% New
36 WHITTIER TRUST CO OF NEVADA INC 0.00% of their portfolio RENO, NV 11 $8 $8 0.00% New