IPO Arc: the rise and fall after listingIPO Arc

SI

Accumulation

SHOULDER INNOVATIONS, INC. · NYSE · priced Jul 31, 2025 · $75M raised · $50M–$250M

Offer price
$15.00
Day 1
+0.3%
close vs offer
Peak
+9.3%
trading day 97
Now vs offer
+36.3%
$20.44 on Oct 29, 2026
Off peak
-25.3%
peak to subsequent low
Lock-up expiry
Jan 27, 2026
276d ago · from prospectus

Price since listing

  • Hype
  • Distribution
  • Lock-up window
  • Valley
  • Accumulation
  • Recovery

Volume bars are coloured by lifecycle phase. Markers: lock-up and early release (orange), earnings releases (E), follow-on offerings (F), research signals (rule id and signal; arrow up = buy signal, arrow down = sell or short signal, or sell signal for deals under $50M). Current phase: Accumulation.

Performance since the IPO

  • SI
  • S&P 500 (SPY)
  • Typical IPO $50m–$250m
  • Middle 50% of those IPOs

SI measured from its offer price; S&P 500 from the first trading day. The typical-IPO line is the median of 453 $50m–$250m IPOs from 2014–2025, by trading day.

Company

Sector
—
Industry
—
Country
—
Employees
—
Market cap
$405M
Website
—

From the prospectus

Lock-up
180 days
Early release on earnings
No
Price-based early release
No
Staggered release
No
Float sold in IPO
25%
Locked shares per share sold
3.0×
Backed by
Venture capital
Lead underwriters
Morgan Stanley & Co. LLC, Goldman Sachs & Co. LLC, Piper Sandler & Co.
Dual-class shares
No
Controlled company
No
Foreign private issuer
No

Extracted from the final prospectus on SEC EDGAR.

Returns vs offer, compared with 90 IPOs $50m–$250m

HorizonSIPeer medianPeers below offer
Day 1+0.3%+0.4%36% n=90
Day 20+5.1%+0.3%46% n=87
Day 60-16.3%+3.4%43% n=83
Day 120-4.1%-6.9%58% n=73
Day 1800.0%-13.1%56% n=64

Research signals

  • BuyRule T1: buy signal for 60 sessions
    Dec 26, 2025 · Pre-unlock quality
    Past signals (642, deals of $50M and over): rose 47% · median -2.6% · dropped 25%+ during the hold 35%
    backtest

    Buy signals passed on returns relative to IPOs of the same year, size and age, most of which fall after listing. A buy signal can beat its peers and still lose money.

  • BuyRule RL: buy signal for 60 sessions
    Dec 26, 2025 · Pre-unlock risk tier
    Past signals (329, deals of $50M and over): rose 54% · median +1.3% · dropped 25%+ during the hold 22%
    backtest

    Buy signals passed on returns relative to IPOs of the same year, size and age, most of which fall after listing. A buy signal can beat its peers and still lose money.

  • Sell or shortRule E1: sell or short signal for 60 sessions
    Sep 10, 2025 · Weak earnings reaction
    Past signals (186, deals of $50M and over): fell 70% · median -13.6% · rallied 25%+ during the hold 33%
    backtest

    Short-selling risk: losses on a short position have no limit and can exceed the amount put up; brokers can demand more margin, recall borrowed shares or close the position; borrow fees and any dividends are owed while short and are not in the figures shown; recent IPOs are often hard to borrow and prone to squeezes.

Rules frozen as v1; signals dated from Oct 29, 2026 are live, earlier ones show what the frozen rules would have flagged. See methodology.

The rules run independently, so one IPO can carry buy and sell signals at the same time; each label reports only its own rule's history.

Past figures cover all 4,312 signals the published frozen v1 rules produce on 2014–2025 IPOs, close to close over each signal's holding period. Returns start at the close of the signal session; signals are published after that close, so the first price available to a reader is the next session's. Only 1,192 of 2,368 operating-company IPOs from those years have usable Yahoo Finance price data; most of the rest no longer trade under their IPO ticker (delisted, acquired or renamed), so the figures probably understate declines. These are hypothetical results, not trades: the rules were selected on these same years with the benefit of hindsight, so the figures likely overstate what live signals will do. The live track record is the real test. Trading costs and borrow fees are not included. Past results do not predict future results.

Research signals only, not investment advice. Lock-up terms come from prospectuses; prices from Yahoo Finance and may be delayed or wrong.