Most managers look at patents as a way of protecting the results of the efforts of their scientists and engineers -- as a legal device to keep competitors from marketing a similar mechanical gizmo or a technique for putting certain molecules together.

But now the creations of the economists, accountants and actuaries are being given the same attention.

Increasingly, patents are being used to give players in the financial markets exclusive control of an innovative securities product.

Lazard Freres & Co., Citibank, Merrill Lynch, Pierce, Fenner & Smith and Trans Texas Holding Corp. have all in recent years had the inventors take out patents on unique financial systems.

"There is a growing tendency for creators, underwriters and marketers of financial products to use intellectual property law to prevent competitors from offering similar or related products and services," according to a study that the law firm of Sutherland, Asbill & Brennan sent out to clients last week. The trend is likely to gain momentum as more firms urge their clients to take the step.

Sutherland, Asbill certainly is unequivocal: "Patent protection offers the most promising means for obtaining exclusive rights to a type of financial product or service for a significant period of time," said the report by Peter K. Trzyna.

The new products so often make use of computer programs that they seem to exist on a frontier between finance and electronics.

The programs cannot be patented because they are deemed to be nothing more than equations, and therefore more like a rule of nature than an innovative combination of diverse elements. But the Patent Office will give its blessing to computers controlled by novel programs.

Merrill Lynch was a pioneer in using that loophole to patent its cash-management system.

Paine, Webber, Jackson & Curtis led the fight against the Merrill Lynch patent, saying it was just a way of doing business and a set of equations.

But the U.S. District Court in Wilmington in a 1983 ruling refused to accept that argument.

The ruling means that other companies can try to match the Merrill Lynch product, but they would have to do the computation by hand.

The Lazard Freres patent covers a method of restructuring debt obligation by figuring the face value of zero-coupon bonds, generating the related documentation, and even printing the certificates for the replacement debt. Citibank two years ago patented its automated investment system.

Last year College Savings Bank took legal action -- since settled -- against CenTrust Savings Bank for allegedly infringing on College Savings Bank's patent entitled "Method And Apparatus For Funding a Future Liability of Uncertain Cost."

College Savings Bank said that patent gave it the exclusive right to market a certificate of deposit with a variable interest rate that was linked to an index of the costs at 500 U.S. private colleges. It claimed that CenTrust's College Prep Account infringed on that patent.

That suit points up the second prong of the Sutherland, Asbill advice: Not only are patents a good idea for originators of a new financial product, but they are a danger to those entering the market later.

"Patents have the potential for causing the greatest reverberations in the financial industry," last week's report said.

"Competitors could well find themselves foreclosed from marketing a product or class of products for 17 years, or perhaps could do so only by paying royalties under a license," said the report. "... As patents become more common in the financial industry, increased care should be taken when deciding to compete with a new product or service."

When a new financial service cannot win a patent, it still can be protected with other legal devices. Five years ago, the U.S. District Court in Manhattan, in Merritt Forbes v. Neuman Investment, ruled that reoffering circulars for municipal bonds could be registered with the copyright office and it would be a violation if other brokerage houses copied significant chunks of these circulars in their own circulars.

Other companies are using trademark registration to gain some exclusivity in customers' minds. Drexel Burnham Lambert, which virtually created the junk bond market, in 1986 registered the mark FASTBAC for First Automotive Short Term Bonds and Certificates.

Even without some sort of advance registration, a distinctive financial service may be protected against encroachment by using claims of unfair competition.

That's the way Standard and Poor's Corp. kept Commodity Exchange Inc. from marketing without authorization futures for a stock index that duplicated the S&P 500.

And it is the same reasoning Dow Jones & Co. used against Chicago Board of Trade plans to sell a product based on the popular Dow Jones industrial average. Daniel B. Moskowitz is a Washington editor for Business Week newsletters.