Check out which companies are making headlines after the bell Monday:
Red Hat: The software company announced a $300 million share repurchase program. Shares edged higher in extended-hours trading.
(Read More: Worst One-Day Drop in 2013: Stocks Skid 2%, Dow Tumbles 250; Vix Spikes 40%)
HCA Holdings: The health-care facilities operator said it expects to post sales of $8.44 billion in the first quarter, versus expectations for $8.68 billion. Shares declined in extended-hours trading.
Netgear: The computer networking equipment company said it expects to earn between 45 cents and 50 cents a share on revenue of $290 million to $295 million in the first quarter, against expectations for 59 cents a share on sales of $300 million. Shares tumbled in extended-hours trading after being briefly halted.
Mack-Cali - The real estate investment trust said it will cut its quarterly dividend to 30 cents a share from 45 cents a share, sending shares sharply lower in extended-hours trading.
Stericycle: Jefferies initiated coverage of the medical waste disposal company with a "buy" rating and a price target of $127.
Alleghany: The investment holding company apppointed John Sennott as its CFO. Sennott will succeed Roger Gorham, who will assume overall responsibility for the company's fixed income portfolio.
Sarepta Therapeutics: The FDA asked the medical research and drug development company for additional information on its experimental drug, eteplirsen, intended to treat young boys suffering from a rare degenerative disease. Shares tumbled in extended-hours trading.
—By CNBC's JeeYeon Park (Follow JeeYeon on Twitter: @JeeYeonParkCNBC)
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