Twitter faces a tough CEO search after announcing chief executive Dick Costolo would step down, Internet analyst Mark Mahaney said Friday.
The company will likely need someone with product and advertising experience, the RBC Capital Markets analyst said on CNBC's "Squawk Box." The candidate should also have held the top spot at another public company, Mahaney added.
"That makes it a pretty short list of people who could come in and turn this around, and it also is going to take quite some time," he said. "That's probably a year, year and a half turnaround. It's a very hard job."
For that reason, Mahaney does not recommend the stock.
To be sure, the role presents an opportunity for the right person, he said.
"Some people talk about Twitter being niche. Come on, it's 300 million people. It's still growing reasonably year over year," he said.
Twitter announced Thursday Costolo would leave his post on July 1. Twitter co-founder and Chairman Jack Dorsey will be interim chief executive while the company searches for a replacement.
The social media company had been under pressure from shareholders to replace Costolo for some time. Investors worry about the company's ability to grow its user base, and advertisers appear unconvinced Twitter can produce meaningful return on investment, RBC Capital Markets said in a note.
Sources told CNBC Costolo made the decision to leave the position, and had been considering it for a while. Costolo will remain on the board of directors, which includes two other former CEOs, Dorsey and Evan Williams.
That creates a potentially awkward situation for an incoming CEO, said Mahaney. The new chief would likely want to hold the chairman position, as well, he added.
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"This is a company and a brand that's got ubiquitous reach, but a lot of execution challenges," he said. "I've never seen as much C-level turnover in a company 18 months post an IPO as you've got now with Twitter."
The company has also replaced its chief operating, financial and marketing officers.
Some market watchers have speculate that current CFO Anthony Noto, who has a Wall Street background, could replace Costolo.