Microsoft just got a $7.6 billion rude awakening related to its purchase of Nokia. The software giant is writing off most of what it paid for a big piece of the Finnish mobile company in 2014.

Microsoft’s total merger-related write-downs now tally about $14 billion over the last three years.

The $9.5 billion Nokia deal was the last in a string of bad deals struck by the previous chief executive, Steven A. Ballmer. As part of the deal, Microsoft received $1.5 billion in cash and paid about $2 billion to license Nokia’s patents and maps. Essentially, the financial cost disclosed on Wednesday — and the accompanying round of 7,800 layoffs — means the handset business is almost worthless and that Microsoft overpaid for the intellectual property.

Mr. Ballmer agreed to the deal as he was stepping down as chief. It was almost a fitting dud to end his tenure.

Under his watch, Microsoft repeatedly tried to move beyond its strength in business software through acquisitions. In 2012, it wrote off nearly all of the $6.3 billion it had paid for the digital advertising agency aQuantive. And there are few signs that the $8.5 billion Microsoft spent on Skype in 2011 is paying off yet.