Stock Market Power Rankings: Amazon Takes Control

Each week, I'm ranking the biggest companies that trade on U.S. exchanges based on their size ( market capitalization), momentum (total return over the past year), and recent news. Before we get to the rankings, a quick word on a major player.

The race for the market cap crown among Microsoft (NASDAQ: MSFT), Apple (NASDAQ: AAPL) and Amazon.com (NASDAQ: AMZN) is intensifying. The three tech bellwethers had market caps $172.2 billion apart when I initiated this weekly list five weeks ago. The gap is now less than $10 billion.

Apple's sharp correction on concerns of waning iPhone demand while Microsoft and Amazon hold relatively steady have changed the narrative. Apple is no longer the most valuable company in terms of market cap, and at several points over the past week it was bringing up the rear, before squeezing past Amazon for the silver medal in a photo finish.