CHICAGO, JUNE 10 -- Ending a nearly three-year investigation by the Securities and Exchange Commission, First Chicago Corp. today agreed to restate its financial results for 1983 and 1984 to reflect a faster increase of its loan-loss reserves over those two years.

The SEC, in an opinion issued today, said the bank holding company should have set aside reserves to cover probable losses on at least seven major troubled loans in 1983 instead of in the third quarter of 1984, when the bank added $308 million to its reserve and posted a $71.8 million net loss.

First Chicago, without admitting or denying the SEC's statement of facts and conclusions, agreed to reduce its 1983 net income by $46.6 million and to increase its 1984 net income by the same amount to reflect the timing change.

Previously, First Chicago reported $183.5 million of net income in 1983 and $86.4 million in 1984.

First Chicago said it agreed to settle the SEC investigation, which the bank previously disclosed, to avoid the cost of further contesting the dispute over its financial statements in those years. It said the settlement has no effect on the bank's current or future financial position.

"Our view is that determining the collectibility of a loan is clearly a matter for judgment, and reasonable people can have different views," said William J. McDonough, First Chicago's vice chairman. "Clearly, the people who are best qualified to make such judgments are experienced bankers. We make reasonable judgments about the collectibility of our loans."

Bruce Hiler, assistant director for enforcement at the SEC in Washington, said: "The commission has seen the need to inject some discipline in that area. We recognize this is a judgmental area, but we want it to be documented and we want you to have reasonable and objective evidence for the judgments you're making."

The SEC singled out $76.5 million in troubled loans to the Hunt family of Texas, saying the bank at the end of 1983 should have set aside $45 million in specific reserves against possible losses on loans to a family-controlled holding company engaged in the sugar-processing business.

Although the SEC didn't name the Hunts, First Chicago was a major lender to Hunt International Resources Corp. and its principal subsidiary, Great Western Sugar Co.

The SEC said interest payments on the $76.5 million were near default at the end of 1983, yet "senior management {of the bank} placed significant reliance on an oral assurance by the family which controlled the borrower to stand personally behind the loans as a basis for not providing a reserve against the loan at year-end 1983."

In another case, concerning an unidentified multinational petroleum company, the bank "gave undue consideration to possible positive future events" that might rescue a troubled $34.5 million loan. The SEC said about $10.5 million should have been set aside at the end of 1983 as a reserve against losses on that loan.

In all, the SEC said the bank should have boosted its year-end 1983 loan-loss reserve by at least $89.6 million more than it did to reflect problems with the seven major loans. Increasing the loss reserve lowers a bank's net income.

The commission also said the bank at the end of 1983 lacked proper procedures to ensure that the method of determining loan-loss reserves met generally accepted accounting principles.

McDonough said, however, that nothing in the SEC's inquiry or findings has prompted the bank to change its practices in reviewing loans or setting loss reserves, although those practices have been "enhanced."

"The kinds of things that go into the credit file now are the same as they were then {when the SEC probe began}," McDonough said.