Here are January’s best and worst stocks — and what may lie ahead for them - MarketWatch

1. S&P 500 gained 2.8% in January despite Nvidia's 17% decline. 2. DeepSeek's AI tech news raised hardware spending concerns. 3. Nvidia’s stock remains volatile, impacting the tech sector sentiment. 4. Constellation Energy saw significant gains but faced recent volatility. 5. Healthcare sector considered bargain-priced, with potential for growth.