TPST Rips Premarket on Senlang CAR-T Option Deal — Float Already Rotated Once Before the Bell

Tempest Therapeutics is the biotech gapper of the morning, trading up more than 40% in premarket after a genuine catalyst hit the wire minutes after Tuesday’s close. This isn’t a no-news drift — on September 15 Tempest announced an exclusive option agreement with Hebei Senlang Biotechnology giving it the right to license Senlang’s CD7-targeted lentiviral vector platform and a portfolio of in vivo CAR-T product candidates. The tape reacted immediately: Tuesday’s regular session had closed at $0.76, pennies off the 52-week low, and the stock ran hard in after-hours before extending premarket. As of this writing (7:50 AM ET, September 16), it’s holding just above a buck after tagging the mid-$1.30s early.

The deal has actual clinical meat on it. The portfolio includes a BCMA/GPRC5D dual-targeting in vivo CAR-T program in Phase 1 dose escalation for relapsed/refractory multiple myeloma, and early observations at the highest evaluable dose show successful in vivo CAR-T generation and expansion, with no Grade 3 or higher cytokine release syndrome and no neurotoxicity observed as of August 25, 2026. Context matters here: Tempest has spent 2026 pivoting from small molecules into in vivo CAR-T. If the option is exercised, the lentiviral platform would complement its CD7-targeted lipid nanoparticle CAR-T platform, which is planned to enter the clinic later in 2026, and its July collaboration with the same partner has TPST-4003 heading into a first-in-human trial in myasthenia gravis and multiple sclerosis patients, with first dosing expected in the fourth quarter of 2026.

The levels

Premarket structure gives you a clean bracket. The early spike into the mid-$1.30s is your ceiling — that’s where the overnight buyers got exhausted and price faded back toward a buck. Below, the premarket floor sits right around the $1.00–1.02 shelf, and it’s psychologically loaded: lose a dollar and you’re staring at a gap-fill magnet back toward the $0.76 prior close.

• $1.34 area — premarket high. A reclaim on volume after the open is the continuation signal.
• Mid-$1.10s — the premarket volume-weighted battleground. Trading above it says buyers still control the session.
• $1.00–1.02 — the floor. Failure here and the gap-fill scenario is live.

Watch the first 15 minutes closely. Price is currently sitting below premarket VWAP, which tells you the early spike sellers are winning the overnight auction so far. Sub-10M float names with this kind of turnover either reclaim VWAP fast and go, or bleed all day.

The supply problem

Here’s what you size against. Just last Thursday, September 11, Tempest executed a warrant-inducement equity financing in late May and then announced a private placement — $2.5 million upfront, up to roughly $7.5 million total if warrants are exercised in full. An S-1 filed August 21 went effective August 31 with a 424B3 resale prospectus on September 1, meaning holder shares are registered and free to hit the bid into this strength. A company that raised at last week’s basement prices has warrant holders sitting on instant paper gains this morning. That’s real overhead supply, and with FY net losses running around $26 million against a $2.5 million raise, more financing is a when, not an if.

The setup: real catalyst, tiny float, massive participation — but registered resale shares and fresh warrants overhead. Level-to-level is the only way to treat it. Hold the dollar, reclaim VWAP, and the premarket high is the target; lose the dollar and step aside.

This is not investment advice; do your own research and size for extreme volatility.

The Setup: This is a Float Squeeze play — read the pattern guide to learn how these setups typically unfold.