Dow crosses 30,000, and Elon Musk is richer than Bill Gates: CNBC After Hours

CNBC.com's MacKenzie Sigalos brings you the day's top business news headlines. Today was a historic day on Wall Street — the Dow crossed 30,000 for the first time on record. CNBC.com's Pippa Stevens explains what Dow points are, why they're important, and why 30,000 is such a significant milestone. Plus, CNBC Wealth Editor Robert Frank breaks down how Tesla's meteoric stock performance added billions to Elon Musk's personal fortune, making him richer than Bill Gates, at least on paper.