Check out which companies are making headlines after the bell Monday:
Nuance Communications - Billionaire investor Carl Icahn took a 9.27 percent passive stake in the speech recognition software company, sending shares sharply higher in extended-hours trading.
Nasdaq - Nasdaq will acquire eSpeed from BGC Partners in a deal worth $750 million, which will allow the firm an entry point into the electronic fixed income business. BGC shares skyrocketed in extended-hours trading, while Nasdaq shares were largely unchanged after being temporarily halted.
(Read More: Stocks End Down After Weak ISM; AAPL Drops)
Medicare-focused insurance companies such as Humana and United Health rallied in extended-hours trading after the Centers for Medicare and Medicaid Services released a final estimated payment growth rate of 3.3 percent for insurers. In February, the government proposed a payment reduction of more than 2 percent.