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Eric D. Shaff

MCRB
CEO AND PRESIDENT · SERES THERAPEUTICS, INC. · CIK 0001643734
FILING MIX · LIFETIME47%/53%
BUYS
28
SELLS
31
TOTAL VALUE
$259.2K
COMPANIES
1
ACTIVE SINCE
Jan 2020
HOLDINGS NOW
12,040
AVG SELL PX
$1.18
TRADE KIND
SHOWING 59 / 59
Trades · vs SPY
Loading price series…
Performance · forward returns vs SPY
11 backtested trades · 8 horizons · 12 pending
Forward-return performance of every backtestable P/S trade by Eric D. Shaff, measured at 8 horizons from 7 days to 2 years. Deduped per economic event so co-filings count once. Excess return = trade return minus SPY return over the same window.
HORIZONTRADESWIN RATEINSIDER RETURNSPY RETURNMEAN EXCESSMEDIAN EXCESST-STAT
7d11+45.45%+4.75%+0.03%+4.72%-0.72%—
14d11+54.55%+3.30%+0.98%+2.33%-3.08%—
30d11+54.55%+1.18%+1.38%-0.20%-2.92%—
60d11+45.45%+7.47%+2.90%+4.56%+1.33%—
90d11+63.64%+2.60%+5.67%-3.07%-18.13%—
180d11(1 pending)+80.00%-13.93%+9.01%-22.94%-30.39%—
1y11(3 pending)+62.50%-5.88%+20.63%-26.51%-33.89%—
2y11(8 pending)+100.00%-53.17%+49.75%-102.92%-99.98%—
How to read this: Insider Returnis the average raw return of the filer's trades over the horizon. SPY Return is what SPY did over those same windows — reference only, not a comparison. The headline alpha number is Mean Excess = Insider − SPY; green means the filer beat SPY, red means they trailed it. Win rate is the share of individual trades where the filer beat SPY. T-statvalues above 2 mean the alpha is unlikely to be chance given the sample size. "Pending" counts trades where the horizon hasn't elapsed yet; their stats are not included in the row average.
Holdings over time
MCRB · 12,040 shares · as of May 18, 2026
0487,500975,0001,462,5001,950,000202120222023202420252026SHARES HELD
Trading cadence · quarterly flow
BUY ● SELL ●
2020
2020
2020
2020
2021
2021
2021
2021
2022
2022
2022
2022
2023
2023
2023
2023
2024
2024
2024
2024
2025
2025
2025
2025
2026
2026
FLOW · 28 buys / 31 sellsCOVERAGE · 26 quarters
Form 4 filings · all activity
COMPANYTYPESHARESPRICEVALUEHELD AFTERTRADE DATEFILEDDETAILS
MCRB
SERES THERAPEUTICS, INC.
SALE10b5-1
10b5-1 plan
259$7.53$2.0K12,040May 18, 2026May 19, 2026 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASE
722——12,299May 15, 2026May 19, 2026 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE
391——1,173May 15, 2026May 19, 2026 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE
331——2,325May 15, 2026May 19, 2026 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE10b5-1
10b5-1 plan
259$8.47$2.2K11,577Feb 15, 2026Feb 18, 2026 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE
391——1,564Feb 15, 2026Feb 18, 2026 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE
333——2,656Feb 15, 2026Feb 18, 2026 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASE
723——11,836Feb 15, 2026Feb 18, 2026 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE10b5-1
10b5-1 plan
217$17.30$3.8K11,113Nov 15, 2025Nov 18, 2025 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASE
390——10,999Nov 15, 2025Nov 18, 2025 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASE
331——11,330Nov 15, 2025Nov 18, 2025 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE
331——2,989Nov 15, 2025Nov 18, 2025 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE
390——1,954Nov 15, 2025Nov 18, 2025 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE10b5-1
10b5-1 plan
217$16.65$3.6K10,609Aug 18, 2025Aug 19, 2025 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASE
333——10,826Aug 15, 2025Aug 19, 2025 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASE
391——10,493Aug 15, 2025Aug 19, 2025 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE
333——3,320Aug 15, 2025Aug 19, 2025 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE
391——2,344Aug 15, 2025Aug 19, 2025 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE10b5-1
10b5-1 plan
220$7.28$1.6K10,102May 16, 2025May 19, 2025 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE
CEO and President
390——2,735May 15, 2025May 19, 2025 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE
CEO and President
331——3,653May 15, 2025May 19, 2025 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASE
CEO and President
331——10,322May 15, 2025May 19, 2025 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASE
CEO and President
390——9,991May 15, 2025May 19, 2025 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE10b5-1
10b5-1 plan
12,726$0.81$10.3K192,039Feb 18, 2025Feb 19, 2025 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE
CEO and President
26,563——79,687Feb 15, 2025Feb 19, 2025 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASE
CEO and President
26,563——204,765Feb 15, 2025Feb 19, 2025 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE
CEO and President
7,813——62,500Feb 15, 2025Feb 19, 2025 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASE
CEO and President
7,813——178,202Feb 15, 2025Feb 19, 2025 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASEGRANT
Stock grant
1,950,000——1,950,000Feb 7, 2025Feb 11, 2025 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE10b5-1
10b5-1 plan
2,505$0.54$1.4K170,389Nov 18, 2024Nov 19, 2024 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE
CEO and President
7,812——70,313Nov 15, 2024Nov 19, 2024 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASE
CEO and President
7,812——172,894Nov 15, 2024Nov 19, 2024 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE10b5-1
10b5-1 plan
8,748$0.69$6.0K165,082Oct 28, 2024Oct 29, 2024 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE
CEO and President
27,837——0Oct 27, 2024Oct 29, 2024 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASE
CEO and President
27,837——173,830Oct 27, 2024Oct 29, 2024 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE10b5-1
10b5-1 plan
2,518$0.84$2.1K145,993Aug 16, 2024Aug 19, 2024 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASE
CEO and President
7,813——148,511Aug 15, 2024Aug 19, 2024 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE
CEO and President
7,813——78,125Aug 15, 2024Aug 19, 2024 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE10b5-1
10b5-1 plan
2,435$0.94$2.3K140,698May 15, 2024May 17, 2024 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASE
CEO and President
7,812——143,133May 15, 2024May 17, 2024 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE
CEO and President
7,812——85,938May 15, 2024May 17, 2024 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE10b5-1
10b5-1 plan
11,549$1.08$12.5K135,321Feb 16, 2024Feb 16, 2024 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE
CEO and President
31,250——93,750Feb 15, 2024Feb 16, 2024 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASE
CEO and President
31,250——146,870Feb 15, 2024Feb 16, 2024 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASEGRANT
Stock grant
106,250——106,250Feb 14, 2024Feb 16, 2024 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASEGRANT
Stock grant
637,500——637,500Feb 14, 2024Feb 16, 2024 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASEGRANT
Stock grant
822,580——822,580Feb 14, 2024Feb 16, 2024 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE10b5-1
10b5-1 plan
8,552$1.35$11.5K115,620Oct 30, 2023Oct 31, 2023 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASE
CEO and President
27,838——124,172Oct 27, 2023Oct 31, 2023 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE
CEO and President
27,838——27,837Oct 27, 2023Oct 31, 2023 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASEGRANT
Stock grant
55,675——55,675Apr 27, 2023Oct 31, 2023 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASEGRANT
Stock grant
250,000——250,000Feb 3, 2023Feb 7, 2023 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASEGRANT
Stock grant
125,000——125,000Feb 3, 2023Feb 7, 2023 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASEGRANT
Stock grant
63,492$3.15$200.0K96,334Jul 5, 2022Jul 6, 2022 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASEGRANT
Stock grant
500,000——500,000Feb 4, 2022Feb 8, 2022 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASEGRANT
Stock grant
350,000——350,000Feb 4, 2021Feb 8, 2021 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASEGRANT
Stock grant
1,000,000——1,000,000Jan 29, 2020Jan 31, 2020 ↗View →
MCRB
SERES THERAPEUTICS, INC.
PURCHASE
CEO and President
20,000——32,842Jan 26, 2020Jan 28, 2020 ↗View →
MCRB
SERES THERAPEUTICS, INC.
SALE
CEO and President
20,000——0Jan 26, 2020Jan 28, 2020 ↗View →
Other insiders · MCRB
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About this filer
CIK 0001643734
ROLE
CEO and President
PRIMARY
MCRB
COMPANIES
1
ACTIVE SINCE
Jan 2020
MARKETPEEL · /INSIDER/0001643734DATA · SEC EDGAR · FORM 4 · CONSOLIDATED TAPE
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