Boston — IBM Corp. disclosed yesterday that it is taking on $11.5 billion in new debt to finance an aggressive acceleration of its stock repurchase plan, which the company believes is one of the largest such steps ever.

IBM had already announced that it would be ramping up its already massive stock buyback, and the technology company also had said it expected to borrow money to get it done. But a filing with the Securities and Exchange Commission revealed the big scope of the project.

Like many other large companies, Armonk, N.Y.-based IBM is on a buyback binge. It has spent $80 billion on its own stock since 1995. By taking shares out of circulation, the move increases the company's earnings per share and gives IBM more shares it can dole out in stock options.

In April, largely to please investors tired of IBM's so-so stock performance, the company's board authorized $15 billion in new repurchases — two and a half times what IBM spends annually on research and development. Recently IBM has been spending about $100 million a day buying its own shares on the open market.

Now, as part of a private transaction known as an accelerated share repurchase, IBM contracted with three banks to buy $12.5 billion worth of its stock — 8 percent of all outstanding shares. Of the $12.5 billion, IBM paid $1 billion in cash and borrowed the rest through an international subsidiary.