Why Yandex, Menlo Therapeutics, and MGIC Investment Slumped Today

Monday was a positive day on Wall Street, as major benchmarks jumped following an uneventful weekend, tapering their gains as the session came to a close. Some had feared that China might retaliate once again after the U.S. issued a second round of tariffs against the nation with the world's second-largest economy, but the expected fireworks didn't come, putting market participants more at ease.

The beginning of earnings season in the next week will also distract investors from geopolitical issues, perhaps allowing indexes to climb further. Yet some individual stocks had difficulties that sent their shares lower. Yandex (NASDAQ: YNDX), Menlo Therapeutics (NASDAQ: MNLO), and MGIC Investment (NYSE: MTG)were among the worst performers on the day. Here's why they did so poorly.