Hewlett-Packard Co. , the world's largest personal-computer maker, is exploring a spinoff of its PC business, an about-face that highlights how growth has pivoted from the computers that so long ruled the industry toward software and mobile devices, where H-P has largely failed to compete.

H-P said its board is evaluating strategic options for its PC business, which could include a "full or partial separation." It also will abandon efforts to sell tablets and smartphones that challenged Apple Inc.'s iPad and iPhone.

At the same time, H-P agreed to buy U.K. software firm Autonomy Corp. for about $10.25 billion, seeking to move further into the higher-profit business of analyzing data for corporations.

The technology giant has been in tumult since its former chief executive was ousted a year ago over ethics concerns. Since then, H-P shares have slumped as it has changed over much of its board and senior executives and lowered financial targets three times, most recently on Thursday.

Investors reacted coolly to the news, which emerged during market hours. H-P shares fell 9% to $26.73 in after-hours trading Thursday, after declining 6% to $29.51 at 4 p.m. on the New York Stock Exchange, amid a broad market selloff.