Legendary money-manager Peter Lynch was fond of sharing his favorite indicator of whether the stock market was overvalued, undervalued or properly valued. He called it the “party test.” Here’s how it worked: When he would go to a party and answered someone’s questions about what he does by telling them that he was the money manager for the Fidelity Magellan fund, their response was the indicator: It they responded with a bit of dread and walked away from him, he knew he wasn’t very popular and...