Hedge-fund manager Dan Niles said on Tuesday that the problem with Alphabet isn't just that it fell way shy of revenue numbers, but that the company didn't give investors enough of an explanation for the miss.
"It's a black box," Niles, founding partner at AlphaOne Capital Partners, told CNBC's Halftime Report. "When something goes wrong, you want an explanation. You're not getting one."
Alphabet shares tumbled 7.5%, the biggest plunge since 2012, after the company said that ad revenue growth slowed to 15% from 24% a year earlier and total sales missed analyst estimates by about $1 billion. Ruth Porat, Alphabet's CFO, attributed the slowdown to a deceleration in click growth at YouTube. But neither she nor CEO Sundar Pichai offered many more details.
Niles said his firm had been reducing its exposure to Alphabet heading into the report and plans to cut it even more. He's frustrated that company executives didn't make clear if this was a one-quarter issue or if it will persist. He noted that in its previous earnings report, investors were skeptical because of the company's capital expenses. Alphabet reeled in its costs and beat on profit in the first quarter, but now revenue growth is causing concern.
Some of his questions for the company relate to the macro online advertising environment, which appears strong. Facebook, Twitter and Snap all reported better-than-expected results in their latest earnings reports, and Amazon's ad growth was impressive, Niles said.
"You look at this and go, well advertising and Google on the internet are obviously synonymous," Niles said. "And when you don't know what's going on, you sit there and go, well I know what's going on at these other names. I'd rather own Facebook, for example."
