Why J.C. Penney, NetEase, and Jounce Therapeutics Slumped Today

Thursday was a relatively quiet day on Wall Street, and action in different parts of the market showed mixed signals for investors. On one hand, small-cap stocks moved higher, with key benchmarks in that area hitting record highs. Yet the better-known large-cap stock indexes like the S&P 500gave up early gains.

Looking more closely at individual stocks, some companies suffered from bad news that sent their shares falling. J.C. Penney (NYSE: JCP), NetEase (NASDAQ: NTES), and Jounce Therapeutics (NASDAQ: JNCE)were among the worst performers on the day. Here's why they did so poorly.