Even as a possible U.S. government shutdown loomed on Capitol Hill, Wall Street managed a modest rise on September 29, 2025. The tech-heavy Nasdaq Composite climbed about 0.5% on the day reuters.com, with investors largely shrugging off fiscal uncertainty. “Investors are clinging to the positives,” noted one strategist, citing hopes of future interest rate cuts and solid economic data reuters.com. Against this cautiously optimistic backdrop, a handful of individual stocks delivered outsized gains thanks to company-specific catalysts – from blockbuster M&A deals to drug approvals and speculative frenzies. Below, we break down the day’s top gainers on U.S. markets and what drove their explosive moves.