Market Insider

Stocks making the biggest moves after hours: American Express, Sleep Number, Alcoa & more

Scott Eells | Bloomberg | Getty Images

Check out the companies making headlines after the bell:

American Express stock gained over 3 percent post-market after the financial services corporation announced its earnings. Both earnings and revenues beat expectations and the company raised its full-year guidance.

This is American Express' first quarter with a new CEO, and it is facing rising competition from other big banks. The company has spent more on rewards and benefits for its consumers in an attempt to fight against the competition, which led to higher expenses than expected.

Shares of Sleep Number plummeted as much as 13 percent after hours on disappointing earnings results. The bed manufacturer missed estimates on both earnings and revenues. Same-store sales fell 3 percent, further disappointing investors. Traditional mattress manufacturers like Sleep Number are seeing increased competition from online mattress retailers.

Alcoa shares hiked 4 percent in the extended session. The aluminum producer announced earnings and revenues that surpassed analyst expectations. In its earnings statement, Alcoa said that it is projecting a growing global deficit for both aluminum and alumina in 2018.

Kinder Morgan stock gained more than 1 percent in extended trading following a mixed earnings announcement. The energy infrastructure company reported earnings that just beat analyst estimates, but revenues fell notably below estimates. It also raised its quarterly dividend by 60 percent.

Shares of Pier 1 Imports plunged more than 17 percent after the bell. The home furnishings retailer reported higher-than-expected earnings but disappointed investors with revenues that fell below Wall Street estimates. Same-store sales also declined 7.5 percent. The company will discontinue its dividend to allocate more resources to a strategic plan to drive growth and value.

United Rentals shares slumped nearly 3 percent in the extended session. The equipment rental company released earnings and revenues that surpassed Wall Street expectations. Rental revenue is also up 25 percent year-over-year.