What Ruth Porat will bring to Google as CFO

Porat very good hire for Google: Pro

Investors can expect Ruth Porat to bring two things to Google as its new CFO, RBC Capital Markets' Mark Mahaney said Tuesday.

"One is cash back to shareholder, not this year, but potentially within the next 12 to 18 months. And secondly, slightly greater financial discipline," Mahaney said in an interview on CNBC's "Squawk Alley."

"The stock trades at around 20 times current-year estimates. That's kind of the higher end of where it traditionally traded. There's clear sentiment for some sort of return of cash to shareholders. Apple went through the same transition when it reached about $80 to $90 billion in cash balances, and that's when it began to return cash," Mahaney added.

Mahaney made his remarks after Porat announced she would be leaving her post at Morgan Stanley to join the tech giant as its chief financial officer. Google's stock was up more than 2 percent in early afternoon trading; Morgan Stanley's was up slightly.

Read More Morgan Stanley CFO Ruth Porat leaves firm for Google

Porat will also make sure Google keeps investing, Mahaney said. "The point isn't simply to come in and crack down on expenses. That would drive shareholder value down at a company like Google," he said.