A public company like Walmart, there's some people doing
some math here.
http://www.zdnet.com/article/yahoo-reports-another-big-loss-... Yahoo also reported that it's writing down $482 million
in charges related to the declining value of Tumblr,
the social-blogging service that Yahoo acquired for
$1.1 billion in 2013.
http://www.theverge.com/2015/7/8/8910999/microsoft-job-cuts-... and the company is writing off $7.6 billion related to
its acquisition of the Nokia phone business. That's more
than the $7.2 billion Microsoft paid for Nokia's phone
business last year.
Public companies "do some math", but that doesn't mean their math is always right. Acquisitions are bets, and bets don't always pay off.