When a company acquires another company, that acquisition becomes a part of the balance sheet of the acquirer. Essentially, the value of the assets they purchased are recorded as if they are worth what they paid for them.
Much of this value, especially with software companies, is carried in the form of "goodwill" on the balance sheet. This is the excess payment over and above the book value of the acquired company (i.e. the value of its assets). If a company gets bought out for $6.3 billion dollars and had $100M in book value assets recorded on their own balance sheet (computers, chairs, buildings, machinery, etc.), then the acquirer records $6.2B in goodwill on their balance sheet,
If the assets that were acquired generate fewer profits than expected, the company may have to record what's called a "goodwill impairment" - the stuff they bought has been demonstrated to be worth less than $6.2B, so they have to record a paper loss in their annual profit and loss statement, which comes out of the goodwill asset on their balance sheet. In theory, the accountants are supposed to look at the business unit every year to see if there is any impairment of value that would require the reporting of a loss associated with the goodwill impairment of that unit. In practice, these things often seem to just sit around for a few years then get pulled out of a hat when the CFO decides fuck it, we're losing money this year anyway, time to write off all that dumb shit we've been carrying on our books that we bought before the economy went kerplop.
Even worse the a goodwill impairment, the entirety of that goodwill can be written off, creating a paper loss equal to almost the amount they originally spent on the company. Which is apparently what happened here.
It's like Microsoft took $6.2B and lit it on fire. They just didn't realize it had all burned up until now, even though the actual cash was gone several years ago.