Know what you own, and know why you own it - Peter Lynch

While catching up on the news is merely depressing to the citizen who has no stocks, it is a dangerous habit for the investor.

When you sell in desperation, you always sell cheap.

First, you find the “market capitalization” (“market cap” for short) by multiplying the number of shares outstanding (let’s say 100 million) by the current stock price (let’s say $100 a share). One hundred million times $100 equals $10 billion, so that’s the market cap for DotCom.com.