Steve Ballmer says Microsoft is 'the only company that ever had any synergy' with Yahoo

Former Microsoft CEO Steve Ballmer still thinks a Microsoft-Yahoo tie-up would have made a lot of sense.

In an interview with CNBC's "Squawk Box" on Friday, Ballmer said Microsoft is the only company that "ever had any synergy" with Yahoo, citing the overlapping search technology and cost reduction it would have produced.

"Microsoft is the only company that ever had any synergy with Yahoo, because you could fold the two search businesses together, get rid of engineers - all the good stuff can happen," he said.

Ballmer, who's now the owner of the Los Angeles Clippers after leaving Microsoft in 2014, famously tried to buy Yahoo for nearly $50 billion in 2008. The goal was to build a Google-competitor by combining Yahoo's search and ad technology with Microsoft's. That deal never materialized as Yahoo kept countering with a higher price.

Instead, Yahoo was sold to Verizon for $4.8 billion this year.

Looking back, Ballmer said it's hard to tell what would have been the right move, especially given how most of Yahoo's value is tied to its ownership stake in Alibaba.

"And yet, most of the value in Yahoo wound up being in Alibaba anyway. So, we would have bought all of that value in Alibaba - not all of which we knew existed. But with 20/20 hindsight, who knows whether it was right," he added.