Banc One and First Chicago NBD Corp. on Tuesday cleared the final hurdle to their $20.6 billion merger, securing shareholder approval for the deal that will create the nation's fifth-largest bank.

The shareholders' votes came a day after the Federal Reserve approved the deal on the condition the combined Chicago-based Bank One Corp., with $230 bil-lion in assets, divest 39 branches in Indiana.Banc One Corp. entered the Utah market in April 1993 when it acquired the 35 Valley Bank & Trust office in the state as part of a $1.5 billion stock swap with Phoenix-based Valley National Corp.

By June, 1997, Bank One Utah had increased its branches to 40 but has since sold four to Community First Bank, leaving them with 36 or one more than they started with when they entered the Utah market five years ago.

The Justice Department approved the deal last week, putting the banks on track to complete the merger by late October.

While Banc One Chairman John McCoy has made no secret he covets the chance to grow even further as the banking industry consolidates, analysts say it will take time to fold in First Chicago's operations.

"Banc One and First Chicago will keep their eye on the ball with the current merger, it's the prudent thing to do," said analyst Michael Mayo at Credit Suisse First Boston. "It will take them a year or a year and a half to be comfortable that the benefits from the current merger have been achieved."

Large banks are merging to cut costs, offer consumers lots of automatic teller machines and an array of account and loan options for one-stop shopping.

The new Bank One will be the nation's second-largest credit card issuer and No. 2 in deposits after Citicorp. Executives hope to consolidate overlapping branches and some of the 90,560 jobs between the two banks to achieve savings, although they have not given detailed figures on expected job losses.

First Chicago spokesman Tom Kelly said some of the cuts could come through attrition; he noted job counts could rise in coming months as the combined bank grows in new directions.

The merger plan was announced in April during the crest of Wall Street's bull market. At the time, the stock deal was worth $28.9 billion, but market losses in recent months have sliced it to about $20.6 billion.

On the same day the merger was made public, NationsBank Corp. and BankAmerica Corp. announced a $62.5 billion marriage that would create the country's first coast-to-coast bank.

The two deals came just a week after banking giant Citicorp and broker-insurer Travelers Group said they would combine their businesses into the nation's biggest financial company.

Some banks have criticized the banking consolidations, saying they threaten competition and could result in higher fees to consumers. In addition, several community groups had accused Banc One of abandoning minority communities and disproportionately excluding and denying loan applications of blacks and Hispanics.

But the Justice Department and the Indiana attorney general's office last week approved the merger, pending the sale of the $1.47 billion in Indiana deposits to Union Planters Corp. of Memphis, Tenn.

Indiana is the only state where Banc One and Chicago-based First Chicago have a significant overlap in operations. Banc One is based in Columbus, Ohio.