Key Highlights

● Estrella traded at about $0.68 in the regular session on October 22.

● The stock reached about $0.77 after hours, which is not a closing price.

● Estrella has a market value of roughly $17 million.

● The S&P 500 health care sector hit a record high.

Shares of Estrella Immunopharma (NASDAQ:ESLA) soared on Thursday, October 22, 2026, trading at about $0.68 during the regular session and ranking among the biggest gainers on the Nasdaq Composite. The stock then extended its advance in after-hours trading, reaching about $0.77 after the 4pm ET close.

There was no company-specific announcement. Estrella did not release clinical data, financial results or deal news tied to the rally.

With a market value of roughly $17 million, Estrella is a micro-cap biotech. Stocks of that size, trading below $1, can be highly volatile on thin news, and sharp moves can occur with no identifiable trigger.

A tiny biotech on a big day for health care

Estrella is a small health care company, and shares of early-stage biotech companies often trade on sentiment and expectations as much as on financial results.

Thursday was a strong day for health care as a whole. The S&P 500 health care sector hit a record high, according to market data, as investors rotated out of technology and into defensive sectors. That happened despite a steep drop in Moderna (NASDAQ:MRNA), which tumbled after Phase 3 melanoma vaccine data that it is developing with Merck (NYSE:MRK) appeared before its scheduled presentation.

Small biotech stocks, however, delivered a mixed picture. Several micro-cap drug developers rose sharply, while others fell hard. Estrella's move was much larger than the sector's gain and does not appear to have been tied to any industry-wide news.

The Nasdaq's worst day since June

The broader index was under heavy pressure. The Nasdaq Composite closed at 26,008.86, down 694.00 points, its steepest drop since June 5. The slide ended a seven-session winning streak and erased about $1 trillion in market value, according to market data.

AI and chip stocks led the decline. The heavy spending plans from Meta Platforms (NASDAQ:META) and Lam Research (NASDAQ:LRCX)'s supply-constrained outlook revived fears that the cost of building AI infrastructure is running ahead of returns. IBM (NYSE:IBM)'s chief executive added to the debate; he said customers "are also getting worried if some of the AI spending is completely out of control with no real return."

Breadth on the Nasdaq was negative, with 2,766 decliners against 2,022 advancers, according to market data. The index posted 342 new lows and 82 new highs.

Regular session versus after hours

The two figures for Estrella reflect different points in time. The $0.68 level was an intraday snapshot during the regular session, which runs from 9:30am to 4pm ET. The after-hours move, to about $0.77, took place after the close and is not a closing price.

After-hours trading usually involves far fewer shares than the regular session. That thin liquidity means prices can move sharply on small orders, and moves seen after the bell do not always hold once regular trading resumes the next morning.

Why sub-$1 stocks swing

Stocks priced below $1 tend to attract short-term traders because small changes in price translate into large relative gains. Momentum can build quickly as stocks appear on daily gainer lists, which can draw in more buyers. The same forces can reverse a move just as fast.

Estrella Faces Friday's Regular Session

Investors will look for any announcement from Estrella on its clinical programs or finances, and whether the after-hours gains carry into Friday's regular session. In health care more broadly, full data from Moderna and Merck's melanoma vaccine trial are due Saturday at the ESMO meeting. Market-wide, the Federal Reserve's decision on Wednesday, October 28, is the next major event.