Amazon.com said Thursday it will buy Audible, a digital audio books provider, for $11.50 a share as in move to expand the online retailer's audio downloads available to users.

The Seattle-based online retailer will purchase all of Audible's outstanding shares and will assume the company's outstanding stock-based awards, for an aggregate value of $300 million.

The deal represents a 23 percent premium to Audible's closing stock price of $9.33 Wednesday.

Newark, N.J.-based Audible provides digital audio content, specializing in digital audio editions of books, newspapers and magazines, television and radio programs, and has over 80,000 programs. The company operates websites in the United States, UK, Germany and France. It has about 160 employees with headquarters in New Jersey, and an office in London, England, with 15 employees.

The announcement comes a day after Amazon reported strong fourth-quarter profit growth and a 42 percent rise in revenue. The company's shares lowered in after-hours trading on concerns over its profit margins.

The deal is expected to close in the second quarter.

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