UPDATE 1-Proxy firms back Amerigroup's $4.5 bln sale to WellPoint

(Adds background on shareholder settlement, deal)

Oct 4 (Reuters) - Proxy advisory firms Institutional Shareholder Services Inc and Glass Lewis & Co on Thursday recommended that Amerigroup Corp stockholders approve the $92-per-share cash offer from larger healthcare company WellPoint Inc .

The shareholder vote on the $4.5 billion deal will be held Oct. 23, Amerigroup said in a statement.

The vote had been set for Oct. 9 but was moved as part of a class-action lawsuit settlement, according to a regulatory filing on Tuesday.

Shareholders had filed suit against Amerigroup, WellPoint and Goldman Sachs Group Inc alleging that Goldman, Amerigroup's financial adviser, was "hopelessly conflicted" and did not get the company the best price.

According to the Tuesday filing, WellPoint and Amerigroup on Tuesday reached an agreement with shareholders to reduce the break-up fee on the deal to $97 million from $146 million. Amerigroup also agreed to delay the stockholder meeting and publicly state that it was prepared to receive and consider in good faith any inquiries and superior proposals.

In July, WellPoint announced a deal to buy Amerigroup as part of a bet on an expansion of the U.S. government's health plan for the poor . The companies said last week that they expect the deal to close in the fourth quarter.

On Thursday morning, shares of Amerigroup were trading slightly under the offer price at $91.60 on the New York Stock Exchange.

Amerigroup said it would not release its third-quarter earnings because of the pending acquisition.

(Reporting By Caroline Humer; Editing by Gerald E. McCormick and John Wallace)

((caroline.humer@thomsonreuters.com)(+1 646 223 6181)(Reuters Messaging: caroline.humer.reuters.com@reuters.net))