US stocks: Wall Street rises as yields ease, Moderna lifts healthcare stocks

The S&P 500 healthcare sector experienced a significant surge, closing 3.5% higher, which marked its biggest one-day percentage gain since April 2025. This surge propelled the S&P 500, Nasdaq Composite, and Dow Jones Industrial Average to modestly higher levels on Wednesday, August 19. The rise in healthcare stocks was largely driven by a dramatic rally in Moderna shares, which benefited from an announcement that its personalized mRNA cancer therapy, developed with Merck, successfully reduced the risk of melanoma recurrence and spread in a late-stage trial.

Moderna’s share price surged almost 177%, leading S&P 500 gainers in a record rally for the company. Merck shares jumped 12.6%, making it the biggest percentage gainer in the blue-chip Dow and the third-biggest in the S&P 500. Other healthcare peers, such as Novavax and BioNTech, also saw substantial gains, with Novavax up 10.8% and BioNTech shares soaring 22%.

The easing of government bond yields further fueled the risk-on sentiment, as the 10-year and 30-year Treasury yields fell. Despite initial gains, equity indexes pared some of their gains as the session progressed, with investors taking profits after the initial rally. The Federal Reserve's July meeting minutes revealed deepening concerns about inflation, with several policymakers ready to raise interest rates if inflation did not decline to the US central bank's 2% target.

However, a day after the 30-year Treasury yield hit its highest level since 2007, it fell on Wednesday, providing a boost to riskier assets and the healthcare sector.