First National Bank of Chicago, the nation's 12th-largest bank, yesterday cut its prime lending rate to 9.5 percent, becoming the first major institution -- and thus far the only one -- to act following cuts in other rates by the Federal Reserve Board earlier this week.

Officials at other major banks on both the East and West coasts declined to comment on their reluctance to lower the prime -- a reference rate to which most business and many consumer loans are tied. But analysts said it underscored the bankers' concern about taking a step that would further hurt their already depressed profits.

Delays in reducing the prime are not uncommon, in part because reductions in the prime often come when the economy and the demand for loans are weak. As a result of significant real estate and other loan losses at many large banks, the institutions are trying to keep their earnings from their good loans as high as possible.

At the White House, spokesman Marlin Fitzwater said the Bush administration is not concerned that only one major bank has reduced the prime.

"These things take time," Fitzwater said. "They have to work through the system. ... The markets will take care of that in due course. We are not trying to speed up the process."

The dimension of the current economic slump was underscored yesterday by a Commerce Department report that consumer spending fell in November for the second month in a row, after adjustment for inflation. While the decline was not as large as October's, the figures indicate consumer buying, which accounts for two-thirds of the gross national product, would be down by a hefty 3.6 percent annual rate in the current quarter even if December's level is no lower than last month's.

That is a sharp reversal from the previous quarter when consumer spending rose at a 2.7 percent annual rate and kept the economy as a whole expanding. Many economists, including those in the administration, expect the economy to decline significantly this quarter and at a slower rate in the first three months of 1991.

The report also said that wages and salaries fell again, although also not as much as the month before. After-tax personal income, which fell in September and was down a sharp 0.8 percent in October, was unchanged last month after adjustment for inflation. Economists said that was a sign the worst of the impact of higher oil prices on real incomes was over.

The Commerce Department also said a survey of business intentions to invest in new plants and equipment next year showed they would increase their spending only 0.4 percent above this year's level once rising prices are taken into account.

If realized, that would be the smallest gain in five years. This year's increase will be about 4.1 percent, according to the survey.

"The plans for 1991 reflect increasingly tough times in the economy," said Allen Sinai, chief economist of the Boston Co., a Boston-based economic and investment advisory firm. He predicted that businesses will trim their investment plans as the economy worsens, with a 3 percent to 5 percent cut from the 1990 level likely.

Lower interest rates throughout the economy, including those on loans whose rates are tied to the prime, could help end the economy's slide, analysts said.

The banks' problems with losses may be providing them with another reason not to cut the prime, one they probably would like to do without. Financial analysts said institutions are having to pay higher returns on their large certificates of deposit, a key source of funds for them to lend, because of investor fears about the banks' soundness.

"Banks are pricing their product, their loans, based on their costs," said Sam Kahan, chief economist for Fuji Securities in Chicago. "If we look at the three-month CD rate as their cost of funds, you see that since July it is down only from 8.25 percent to 7.90 percent."

Over that same period, the Federal Reserve has cut its target for the federal funds rate -- the interest rate banks charge when they borrow cash overnight from each other, a type of borrowing that can be a substitute for issuing CDs -- from 8.25 percent to 7 percent. The Fed decision to cut the last quarter point of that decline came Tuesday, along with the announcement that the central bank was lowering its discount rate -- the rate financial institutions pay when they borrow from the Fed itself -- from 7 percent to 6.5 percent.

"The level of the CD rate reflects a general unwillingness to lend to banks," Kahan said. "With all the publicity about bad loans and the problems of the banks, the spread between bank interest rates and the {federal funds} rate has increased. ... That means the banks' opportunity to pass on cost savings to customers is smaller than it appears."

The rates on bank CDs traded in the market jumped yesterday to more than 7.9 percent, up from 7.55 percent late Tuesday after the Fed announced the discount rate cut. At 7.9 percent, the three-month CD rate is just over 2 percentage points lower than the 10 percent prime. A spread of more than 2 percentage points between the CD and prime rates usually is enough to bring the prime down, and most analysts expect other banks will follow First Chicago's soon.