— Why it moved
Why PFSA Stock Tripled Today — August 18, 2026
Profusa went ballistic because yesterday's reverse split stripped its float to almost nothing, not because anyone cares about its biosensor tech.
What moved PFSA stock
Profusa develops tissue-integrated biosensors for continuous health monitoring. The stock didn't move on clinical progress, though. A 1-for-4 reverse stock split went into effect yesterday, and today the company filed a proxy asking shareholders for permission to execute another reverse split down the road. Retail traders latched onto the stripped-down share count.
The mechanics
With a float of just 45,464 shares, relative buying quickly turns into a squeeze. Day traders churned over 53 million shares through a micro-cap valued under $1.2 million.
PFSA by the numbers
The alert window
The alert went out early at 7:02 AM sitting at $9.79. Before the move caught fire, price dipped 13.2% to a low of $8.50. Patience was rewarded 550 minutes later when it peaked at $32.82 during the afterhours session, giving traders plenty of time to capture a massive run.
How PFSA's move ended
Shares faded off the high to close at $26.81, up 173.9% from the alert. The underlying business remains in trouble, as evidenced by a late quarterly filing and the immediate push for another reverse split to dodge Nasdaq delisting.
The tell: A reverse split doesn't fix a dying balance sheet, but the sudden float drop often triggers a short-term liquidity trap.