Microsoft is in the trenches evaluating brand positioning for its search engine, Bing, with some very familiar faces: Ty Montague and Rosemarie Ryan, now with Co Collective, and an agency it used to own: Razorfish.

People familiar with the matter say that Microsoft is doing a deep-dive look at where it wants to take the Bing brand, and that labor won't bear fruit until next year. What's up for debate? Whether to stick with positioning Bing not as a search engine, but as a decision engine.

Microsoft launched Bing with "Decision Engine" ads from Mr. Montague and Ms. Ryan's former agency JWT, but has been marketing the search engine under "Bing and Decide" for at least six months. There's no plan to move away from "Bing and Decide," according to the company.

Co's Mr. Montague was chief creative at JWT when that agency came up with the launch campaign "Decision Engine" back when Bing first launched in 2009. Since then, he left JWT to start the independent shop with Ms. Ryan. The new relationship has sprung up after the pair's one-year non-compete period with WPP expired. The so-called brand innovation studio has grown to about 20 people.

Razorfish is also said to be involved; Microsoft sold the mammoth digital agency sold to ad-holding company Publicis Groupe in 2009. The agency has continued to work with Microsoft on such projects as the ill-fated Kin phone. Razorfish referred calls to the client; Co Collective declined to comment.

Bing has, more or less, steadily gained market share in the U.S. since its launch, but that 's flattened out this year, according to ComScore data. However, since Bing's launch, search leader Google has only continued to grow its hold in the U.S. While Microsoft's search share has grown too -- with 14.4% compared to Google's 65.1% in July per ComScore -- it looks to be at the expense of Yahoo, a Bing partner, whose position as the No. 2 U.S. provider continues to slip over the last few years.