What is the lock‑up period for insiders and early investors, and when might additional share sales be permitted?

Lock‑up terms

Heartflow’s IPO prospectus (the filing referenced in the press release) sets a 180‑day lock‑up on any shares held by insiders, directors, officers and other early investors. During this period those shareholders are prohibited from selling any of their Heartflow stock, except for limited “permitted” transfers (e.g., to spouses, trusts, or for tax‑related purposes) that are expressly allowed in the agreement.

When additional shares can be sold

The lock‑up expires 180 calendar days after the IPO closing date (August 11 2025), so the earliest date that insiders may legally dump their shares is early February 2026. The prospectus also notes that the company may file a follow‑on registration statement (or an S‑1 amendment) before the lock‑up ends, which would allow a secondary offering to be priced and sold once the registration statement becomes effective—often shortly after the lock‑up period ends. In practice, the first wave of secondary sales typically occurs within a few weeks after the 180‑day window closes, when the company can tap the public market for additional capital or allow early investors to monetize their positions.

Trading implications

- Supply pressure: The 180‑day lock‑up creates a “quiet period” for the stock. When the lock‑up lifts, the market may anticipate a modest increase in float, which can put down‑side pressure on HTFL’s price around early‑February 2026. Traders should monitor pre‑lock‑up sentiment; a tight price range and low volatility are common before the expiry.
- Technical cue: Watch the 200‑day moving average and volume spikes around the expected lock‑up expiry. A breakout above resistance with strong volume could indicate that the market is already pricing in the upcoming share‑supply, whereas a breakdown may signal that the market is still expecting the dilution.
- Fundamental context: The IPO raised ≈ $364 million at $19 per share and the underwriters fully exercised their option, indicating strong underwriting demand. However, any secondary offering will dilute earnings per share; analysts should adjust their valuation models for a potential 5‑7 % dilution (the 2.5 M‑share option) plus any subsequent secondary issuance.

Actionable insight: If you are a short‑term trader, consider selling or tightening stops ahead of the early‑February 2026 date, especially if price is near recent highs and volume is low (suggesting limited buying support). Long‑term investors should factor a potential 5‑10 % price dip into entry points, while still weighing Heartflow’s strong AI‑CAD franchise and the cash generated from the IPO. Monitoring the SEC’s filing of any follow‑on registration (typically filed a month or two before the lock‑up expires) will give an early warning of the exact timing of any additional share sales.