Yahoo Inc., one of the world's most heavily trafficked Internet portals, said yesterday that it purchased rights to the data-mining software of McLean-based MicroStrategy Inc., which it will use to evaluate the efficiency of its online purchasing and advertising operations.

Executives at MicroStrategy, which markets a range of software to analyze business data, said Yahoo would become its largest online customer.

"It is validation for us," said Sanju K. Bansal, chief operating officer of MicroStrategy. "We are getting to the heart of Yahoo activity."

Nancy Evars, a spokeswoman for Yahoo, said the company will use MicroStrategy's software to assess the profitability of its advertising and e-commerce divisions, which account for the vast majority of the portal's revenue. The company wants to track trends in individual retail categories.

"The main reason we are using this is to better understand our customers," Evars said.

Neither Yahoo nor MicroStrategy would disclose the cost of the licensing agreement.

MicroStrategy licenses its software to 1,600 clients, including major retail chains such as Best Buy, CVS Pharmacy and Lowe's, as well as online retailers such as BarnesandNoble.com, company spokesman Marc Brailov said. The software is used to examine trends such as purchasing patterns and employee productivity.

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