UPDATE 1-E*Trade sells wealth unit to Adviser Investments

* E*Trade sells adviser unit to local rival

* Combined firm to have $2.3 bln in assets (Rewrites, adds details on deal, backer)

BOSTON, March 21 (Reuters) - Adviser Investments, the wealth manager begun by well-known fund analyst Dan Wiener, is buying a suburban Boston rival, Kobren Insight Management, from E*Trade Financial Corp (ETFC.O).

Terms of were not disclosed.

Adviser Investments of Newton, Massachusetts, has about $1.3 billion under management. Kobren, based in Wellesley, Massachusetts, before the deal, will add about $1 billion in assets to Adviser Investments' base. The smaller firm was founded by Eric Kobren, who had sold the business to E*Trade in late 2005 and retired.

The larger firm's chairman, Wiener, writes a widely read financial newsletter tracking fund giant Vanguard Group. Its chief investment officer, Jim Lowell, writes a separate newsletter following Fidelity Investments.

Wiener said the deal, announced by the companies on Monday, will give Adviser Investments "an even deeper bench," bringing in new fund managers and research analysts.

Kobren Chief Investment Officer Rusty Vanneman will join the new firm as chief investment strategist, said Wiener and Investment Advisers President Dan Silver. Kobren Fixed Income Strategist Chris Keith also will join the new firm, which will keep the Adviser Investments name.

Both firms were started in the 1980s. Silver said the combined firm will have about 45 professionals, including 20 from the Kobren business, and that no layoffs are expected.

Wiener said financing for deal was provided by Fiduciary Network, a Dallas investment firm that focuses on the wealth management industry. It will own about 20 percent of the combined business. (Reporting by Ross Kerber; Editing by Phil Berlowitz and Steve Orlofsky)