This column has been updated from June 4 to reflect Ballmer's additional remarks on Twitter.

Steve Ballmer is defending his deeply-underwater investment in Twitter  (TWTR) once again, and the microblogging platform's shares seem to be getting a boost from them. Nothing that the former Microsoft CEO said about Twitter this time around is especially controversial, but the devil lies in the details.

On Friday, July 14th, Ballmer defended Twitter, arguing that its turnaround efforts are bearing fruit. "[I]mproving the products some and improving and making the monetization better, I think the company has been on top of both of those things. The market understands that. And it is now getting somewhat reflected in the stock price," he said, while admitting Twitter execs still have "their work cut out for them." As a result, Twitter shares have risen 2.2% to $19.74 in morning trading.

In addition to standing by the wayside as Alphabet/Google (GOOGL) came to dominate Internet search, as Facebook  (FB) did the same to social media, and Google and Apple  (AAPL) swept up mobile operating systems, the low-lights of Steve Ballmer's tenure as Microsoft (MSFT) CEO include a string of dubious 10-figure acquisitions. Those deals include the $6.3 billion purchase of online ad agency aQuantive and the $7.2 billion purchase of Nokia's mobile phone unit, both of which resulted in write-downs similar in size to the acquisition price.

Microsoft's $8.5 billion 2011 acquisition of Skype is also looking like a less-than-stellar deal. Though Skype retains significant value and has bolstered Microsoft's business communications offerings, it's not a given that it's worth $8.5 billion or more today, considering how Facebook, Tencent and others have come to dominate mobile messaging.

Even if Ballmer's also-questionable $2 billion purchase of the L.A. Clippers is left out on the grounds that he had nonfinancial motivations, enough bad deals remain on Ballmer's resume to think twice when he gives investment advice about tech companies. To be fair, though, a lot of the bad deals made while Ballmer was Microsoft's CEO did involve markets that he had good reason to grow Microsoft's exposure to, such as online ads, smartphones and Internet voice and video. The faults lie in how the acquisitions positioned Microsoft, and the price that was paid.

Which brings us to Twitter. Nineteen months after disclosing he had amassed a 4% stake in the microblogging platform, Ballmer said in Late May he maintains a "large percentage" stake, and (though denying that Microsoft ever made a bid while he was CEO) that he's confident the company will either resolve its problems on its own or get acquired.

Echoing other Twitter bulls, Ballmer argued there's still "a real opportunity to make [Twitter] a valuable economic asset," and that he continued to believe in its potential since it "gives people a chance to communicate directly with the people they want to talk to in the world." At the same time, he doubted that Jack Dorsey will be able to pull double duty as CEO of both Twitter and Square (SQ) perpetually.

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