Summit Therapeutics Stock Plunges 23%: The Ivonescimab Update Shaking Its Keytruda Challenge

Summit Therapeutics Inc. continues to trade like a classic high-beta biotech: big promises in lung cancer, plenty of red flags, and a stock price stuck near the lower end of its 52-week range while analysts project eye-popping upside.

Summit Therapeutics’ share price has been on a roller-coaster ride this year. After a steady climb through late summer, SMMT spiked above $25 intraday in mid-October, then pulled back to end last week just under $21 ts2.tech. The stock fell 4.5% on Friday, Oct. 17 alone ts2.tech as traders braced for the upcoming data presentation and earnings call. Even after that dip, Summit shares remain up solidly in 2025 – roughly in line with the broader biotech sector ts2.tech.

Summit Therapeutics’ share price has experienced extreme swings this year. After a steady climb through late summer, SMMT spiked to an intraday high above $25 on Oct. 13, 2025, before pulling back to end the week just under $21stockanalysis.com. The stock fell 4.5% on Friday alonestockanalysis.com, capping a choppy few days as traders braced for the ESMO conference and earnings. Despite the recent dip, Summit’s stock is still up double-digits in 2025, roughly in line with the broader biotech sectorfinance.yahoo.com.