Twitter Inc. on Thursday acquired a small startup and immediately installed its founder as its new product chief, filling a crucial role that's been vacant for nearly a year.

Keith Coleman, the chief executive of social-networking app maker Yes Inc. and a former Google product manager, will take over as Twitter's vice president of product. He joins Twitter along with six others from Yes, a two-year-old startup that makes apps including event-planning service Frenzy.

A Twitter spokeswoman declined to disclose the deal price.

The hiring caps a turbulent year for Twitter, which is trying to regain its footing under Chief Executive Jack Dorsey. A revolving door of product chiefs and frequent strategy shifts over the years has stunted Twitter's ability to evolve the service and appeal to mainstream users.

Mr. Coleman is Twitter's sixth product chief since 2007 and fourth since the company's initial public offering in November 2013. Before founding the little-known Yes, Mr. Coleman worked at Alphabet Inc.'s Google, where he oversaw products like Gmail, Inbox and Gchat.

Twitter, whose stock has fallen about 22% this year, has been without a full-time product chief since January, when longtime executive Kevin Weil decamped to run product for Facebook Inc.'s photo-sharing app, Instagram. Mr. Weil was one of four top executives to leave the company at the time. Until now, Twitter technology chief Adam Messinger has been overseeing product.Mr. Dorsey is under pressure to reinvigorate the company's sluggish user growth, which has hovered between flat and 2% since he took over as permanent CEO a little more than a year ago. Investors grew more impatient this fall after companies including Salesforce.com Inc., Walt Disney Co. and Alphabet Inc. considered buying Twitter before backing away.

Soon after, Twitter said it would cut 9% of its workforce, shut down its Vine video app and redirect its focus from driving growth to delivering profits. Last month, Adam Bain, Twitter's well-respected chief operating officer, said he would step down to explore other opportunities. He will be replaced by Chief Financial Officer Anthony Noto, who has been spearheading the social-media company's efforts around live video.

Mr. Dorsey has made video central to Twitter's turnaround effort, aiming to become a prime destination to watch live events. Executives believe there are signs Twitter isturning a corner, with increases in the number of daily users, in time spent on the site, and in impressions over the past couple of quarters, people familiar with the matter say.

Write to Deepa Seetharaman at Deepa.Seetharaman@wsj.com

(END) Dow Jones Newswires

December 01, 2016 20:45 ET (01:45 GMT)

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