(FORTUNE Magazine) – NO, VIRGINIA, there will not be a ''December surprise'' in the U.S. banking business. Despite the dire warnings of Ross Perot, 100 banks will not be shuttered and a bill for $100 billion will not be presented to the federal deposit insurance fund. Indeed, it is entirely possible that the most dramatic, tear-jerking crisis at a financial institution during December will take place, as it does annually, in the nonstop Christmas showings of It's a Wonderful Life.

Even so, hold those cheers. Though December should pass peaceably, important new pressures are bearing down on the banking industry that will accelerate both the failure of weak banks and invasions of the deposit insurance fund. A new law and toughened accounting rules will squeeze infirm institutions. The effects will be compounded if interest rates rise, since that will pinch profits at all banks. The new law is the Federal Deposit Insurance Corp. Improvement Act of 1991, or Fdicia, pronounced Fuh-DISH-uh. Through a ton of draconian provisions, Fdicia requires federal regulators to tighten their surveillance on banks and swear off forbearance of sick institutions. It demands that regulatory accounting principles be no less stringent than the broadly used generally accepted accounting principles (GAAP), and it socks banks with heavy new reporting, legal, and auditing costs. In its harsh totality, the law represents Congress's embarrassed attempt to keep banks from staging a reprise of the $160 billion or so savings-and-loan debacle. So far, bank failures haven't cost taxpayers a nickel: Banks themselves have borne the $35 billion in costs that the bank insurance fund has sustained in the past decade.

Under the law, the FDIC is obliged, give or take some due-process qualifications, to close down promptly any bank whose tangible equity capital -- that is, shareholders' equity minus fluff like goodwill -- falls to 2% or less of its assets. Fast action, so the theory goes, will mitigate raids on the insurance fund and ward off the taxpayer tap. This new tripwire rule kicks in on December 19. But due process will spare many of its victims until 1993. Falling interest rates have made this a good year for bank earnings and capital, so relatively few banks are in what one regulator calls the ''drop- dead 2% category'' anyway. Numbers given Congress by the FDIC's acting chairman, Andrew C. ''Skip'' Hove Jr., show that as of last June, only 60 institutions, holding $25 billion in assets (out of $3.7 trillion in banks insured by the FDIC), fit the description. By the end of October, 20 of those had been finished off by the feds. Most banks seem to have accepted the 2% rule calmly, but what they bitterly despise about Fdicia is its straitjacket of costly regulations. Some of these will make weak banks even weaker. For example, Congress has directed the FDIC to build its insurance fund to 1.25% of insured deposits. Immediate compliance would require the fund to balloon from less than nothing (because reserves that the FDIC has established have given the fund a negative net worth) to $26 billion. Getting there hastily would probably wreck the banking industry, so the FDIC has set up a plan to reach the required ratio in 15 years. But even that slow-boat schedule will force premium rates up by an average 10% in 1993. The weaker the bank, the greater its risk to the insurance fund, so the more it must pay. The most enfeebled, as judged objectively by their capital ratios and subjectively by regulators, will pay a 0.31% premium on their insured deposits, while the healthiest will pay only 0.23%. The difference of 0.08% -- or eight basis points -- may not sound like much, but in an industry that battles annually to make even 60 basis points on assets, it's a crusher. One fallout from Fdicia will surely be a pickup in the consolidation trend that since 1985 has reduced the number of banks from 15,000 to about 12,000. Even the new president of the American Bankers Association, William Brandon, head of a small Helena, Arkansas, bank, claims to be contemplating escape from Washington's ''micromanagement.'' Says he: ''A lot of bankers, like myself, are thinking it's a good time to sell out.'' In a more severe effect, some already struggling banks are going to be driven into the drop-dead 2% territory and fail. Unquestionably, that will accelerate the calls on the deposit insurance fund, though it will not necessarily increase the fund's outlays over the long run. The FDIC estimates that next year it will seize 100 to 125 banks with assets of $76 billion, which would about double the dollar total for this year. It is essential to recognize that the 2% tripwire refers to a bank's stated assets and capital, and takes no account of the possibility that both figures may, in a sense, be overstated. Though some of a bank's assets -- for example, its trading account -- are marked to market every day, other assets, like investment securities, are carried at historical cost or, as in the case of loans, historical values minus reserves for losses. Examiners, by demanding higher reserves on troubles like real estate loans, have introduced some needed realism into balance sheets. But many skeptics think the job unfinished. Says Donald Chapin, an assistant comptroller general of the General Accounting Office: ''I continue to believe that banks have a lot of water in their balance sheets. Some has been wrung out as banks have been forced to recognize their problems. But a lot of water is left.'' Some blurred evidence on that point comes from the FDIC's historical experience in liquidating the assets of banks it has taken over. On every $1 of assets seized, it has suffered an average loss of 17 cents. Some of that dismal result plainly reflects the fire-sale prices that the FDIC has had to accept. But just as plainly, some of the toll is attributable to balance-sheet values that just weren't there. Lately, certain big banks have gone into the fire-sale business themselves, among them First National Bank of Chicago. Seeing no near-term end to the real estate crisis, First Chicago announced in September that it would move more than $2 billion in commercial real estate loans and foreclosed properties into a special ''held for sale'' portfolio, which it plans to unload as quickly as possible. Before this move, the company was carrying these assets, after < write-downs and reserves, at 75% of original loan value. After the move, taking into account $625 million in new reserves, the carrying value is a bleak 49%. You can ask whether First Chicago had previously overstated the value of these assets and is now facing up to reality. Not surprisingly, the company's chief financial officer, W. G. Jurgensen, vehemently rejects that thought, pointing out that the decision to sell quickly, rather than to hold, stripped value from the portfolio. Even so, Walter Schuetze, chief accountant at the Securities and Exchange Commission, found the First Chicago figures unsettling. ''Imagine,'' he said recently, ''only 49 cents on the dollar.'' Schuetze grants that every bank is different, but he still asks what First Chicago's move says about the values at which the other big banks are carrying their real estate.

AN ADDED CRUNCH today for the banks and their regulators is that the main arbiter of GAAP, the Financial Accounting Standards Board, is moving slowly, but seemingly irreversibly, toward more mark-to-market accounting. The SEC itself is a red-hot advocate of this brand of accounting for financial instruments. It has recently forced a raft of banks to abandon historical cost valuations for certain marketable securities and to begin stating these at the lower of their cost or market. The change will produce quarterly swings in profits. If interest rates rise, the prices of government securities -- banks' favorite holding -- will decline and so will reported income. Banks hate volatility in their earnings. The SEC's action has also taken away banks' flexibility to take securities profits when it is most convenient -- that is, when earnings need a little boost. Just how banks feel about the SEC's policies was indicated by a question from the floor to an SEC speaker at a recent American Institute of Certified Public Accountants' meeting for bank accountants. The question, which caused both speaker and audience to roar: ''Do you see any resemblance between the evolving relationship of the SEC and banks and the L.A. police and L.A. residents?'' Bank regulators don't like earnings volatility either, and they have consistently asked whether mark-to-market accounting works for hard-to-value items such as commercial real estate loans. They are nonetheless facing Fdicia's order to make their regulatory accounting principles (RAP) no less severe than GAAP. The RAP rules haven't been issued yet. But if the regulators heed the law, the trend to mark-to-market accounting is in time going to force an increasing number of marginal banks below the 2% limit. That's when the headlines will come, along with blame for auditors, regulators, and banks. The headlines would be hastened by rising interest rates, which in this time of transition and difficulty for the banks are the threat that every regulator fears and cannot necessarily wish away.

CHART: NOT AVAILABLE CREDIT: FORTUNE CHART SOURCE: FEDERAL DEPOSIT INSURANCE CORP. CAPTION: FEWER BANKS ARE FAILING . . . BUT THE FAILURES ARE BIGGER . . . SO THE BAILOUT COSTS ARE RISING . . .