The Federal Deposit Insurance Corp. said yesterday that the fund that insures deposits in the nation's 14,000 banks saw modest growth in the first six months of this year despite a record number of bank failures.

Even though 96 commercial banks failed in the first six months of 1987, the fund grew by about $164 million, hitting a total of $18.4 billion, Stanley J. Poling, the FDIC's accounting chief, told the agency's three-member board. Sixty-six banks failed in the first half of 1986.

FDIC Chairman L. William Seidman said, "Despite the fact that the number of bank failures we're having is up about 50 percent, {the growth of the fund} does give us some confidence that we can handle this kind of difficulty."

Poling attributed the fund's first-half performance to a strong effort to collect bad loans and a greater use of "whole bank" transactions, in which the FDIC subsidizes the sale of failing banks. A more traditional approach had been for the FDIC to take over a failed bank, sell off its performing loans and be stuck with the bad loans.

Poling predicted that the FDIC would finish 1987 by breaking even or posting a modest gain.

"I would not be surprised if our results mirror those of last year," he said. The fund had a net income of $296 million in 1986.

As of Aug. 7, 109 banks had failed this year, and the agency had assisted 16 others. Nearly half of the 109 are in Texas and Oklahoma, states beset by the ailing oil and farm markets. Seidman is predicting about 200 failures by year's end.

The number so far this year represents the worst failure rate since the board began keeping track. About 4,000 banks failed at the peak of the Depression in 1933, the year before the insurance fund began operating.

Last year, a record 138 FDIC-insured banks failed, compared with 120 in 1985, 79 in 1984, 48 in 1983, 42 in 1982 and 10 in 1981. Most of the failures this year have been among smaller banks, in the $30 million to $40 million asset range.

However, a problem with a large bank, the $12.5 billion First City Bancorp of Texas, looms. A government official, who spoke on condition of anonymity, confirmed a report in Tuesday's editions of The Wall Street Journal that the FDIC is negotiating a buyout of the bank. Troubled by losses from real estate and oil loans, it lost $563 million in 1986 and the first half of this year.

Among the options being considered by the FDIC is an assistance package of $1 billion to the bank's new owners, the official said.

The FDIC's report on the condition of its fund follows the recapitalization of the Federal Savings and Loan Insurance Corp., which insures 3,200 savings and loan institutions