Three of the five largest mortgage lenders in the District of Columbia are mortgage banking firms rather than savings and loan associations, a Washington Post computer analysis shows.

In terms of the number of mortgage loans made in the city over the past three years, Colonial Mortgage Service Associates, Inc., is the largest lender in the city. However, in terms of the dollar value of mortgages, Colonial is second to Perpetual Federal Services and Loan.

Among the top 20 mortgage lenders in the city, six were mortgage bankers that made 4,461 mortgage loans totaling $1563 million during the past three years, while 14 were banks and savings and loan associations that made 7,434 loans worth $360.3 million, according to the analysis.

The mortgage bankers, who specialize in federally insured mortgages, appear to be more active in the generally less afluent Southeast, Southwest and Northeast sections of the city than in the wealthier Northwest section, where the banks and savings and loans do a majority of their mortgage lending business, according to the computer analysis.

Local financial institutions say they do not discriminate against black home-buyers and that they are willing to lend in areas of the city outside the Northwest quadrant.

Mortgage bankers continue, however, to dominate the home financing business in black sections of the city, according to several sources, in part because they have strong ties with realtors dealing in black neighborhoods from the days when local banks and savings and loan associations engaged in discriminatory practices. In addition, mortgage bankers are willing to make Federal Housing Administration and Veterans Administration and Veterans Administration guaranteed loans, which banks and savings and loans generally do not make.

For years, spokesmen for the savings and loan industry have told Congress that S&Ls do not purposefully discriminate against low-income or black areas - a practice knowns as redlining - but have argued that federal bank regulatory laws prohibit them from jeopardizing their deposits by investing in "declining" neighborhoods.

Critics of the savings and loan industry have argued that the regulatory laws should be changed - and that, in some cases, S&Ls have interpreted the laws much too narrowly in order to justify discriminatory practices.

To determine the number, dollar amount and geographic location of home mortgages written by mortgage bankers and financial institutions in Washington, a Post computer analyzed all mortgage transactions in the city for the past three years as compiled by Rufus Luck & Son, a D.C. real estate director service.

The comupter totaled the number and dollar value of mortgages made by each lender active in Washington and tallied the number of mortgages written in the Northwest section compared with the number made in the rest of the city.

While this geographic breakdown represents a crude way of determining types of loan recipients, the overall results were confirmed by the lenders themselves.

Since mortgage bankers may sell their loans to a wide variety of investors, there is no way to determine how many of the loans made by mortgage bankers might have been purchased by the S&Ls. Perpetual Federal Savings and Loan Associations, for example, buys a number of mortgages from mortgage bankers. Similarly, there was no way to determine how many loans made by S&Ls might have been sold to other investors.

The analysis showed that in the three year period, Colonial had given 1,223 mortgages, followed by Perpetual with 1,173 mortgages, Virginia Mortgage & Investment Co. with 1,019. National Permanent Federal Savings and Loan Association with 837, and Steed Morgages Co. with 755. All but Perpetual and National Permanent are mortgage bankers.

Because average dollar values of mortgages vary from institution to institution, the lenders ranked differently when compared by the total value of the mortgages they have given.

When compared by total dollar value, Perpetual was the largest lender, followed by Colonial National Permanent, Virginia Mortgage, and Columbia Federal Savings and Loan Association. However, numbers of mortgages, rather than dollar values, give a better indication of how a lender serves the needs of home buyers.

Based on numbers of mortgages, each of the mortgage banking firms in the top five made more than 50 per cent of its loans outside Washington's northwest section, while Perpetual and National Permanent made 38 per cent and 31 per cent of their loans, respectively, outside northwest.

Several S&Ls proved to be exceptions to this pattern. American Federal Savings and Loan Association for example, gave 60 per cent of its loans outside Northwest. Asked to explain this, the institution said it aggressively seeks loan applicants wherever there is a need for housing.

In contrast to the S&Ls, all of the mortgage bankers in the top 20 gave more than 50 per cent of their loans outside Northwest.

Mortgage bankers make loans and then sell them within a month or two to other investors, such as banks, insurance companies, pension funds, government sponsored corporations, individuals, and savings and loan associations.They make their money by charging a fee of 1 per cent of the loan amount for originating a mortgage and about 3/4 of 1 per cent each year for collecting mortgage payments.

The firms got their start after World War II to fill the need for lenders who would make use of new government programs designed to encourage home purchases.

Loans made by mortgage bankers cost the same as those made by S&Ls when they are FHA or VA mortgages; on conventional loans, they generally charge up to an additional 1/4 of 1 per cent interest when compared with S&Ls.

C. William Blomquist, president of Colonial, estimated that about 70 per cent of the Kensington firm's mortgages go to blacks.

Blomquist said Colonial has found Washington mortgage lending is profitable, and the foreclosure rate is about the same as in Montgomery County and the Virginia suburbs.

"S&Ls have given the impression they don't want black or transition areas," Blomquist said. "Discrimination is still there, especially in major metropolitan areas. They'll say we'll only lend in Maryland or Virginia; they don't tell you why."

He added, "I think the S&Ls are living in the past. A lot of them don't rebate to minority groups."

Another mortgage banker, Lewis W. Russell, president and chairman of Virginia Mortgage & Investment Co., Washington's third largest mortgage lender, said, "We go where the business if, and it's in Washington."

John P. Murchison Jr., a prominent black realtor and mortgage banker, said in addition to past discrimination by S&Ls, mortgage bankers tend to be more aggressive in persuading real estate brokers to refer customers to them.

Executives of the two S&Ls that ranked among the top five lenders - Perpetual and National Permanent - each acknowledged that there has been some reluctance historically by some S&Ls to lend to blacks.

"I think the S&Ls have dragged their feet for a long time in lending to black areas of D.C., but there's been a significant change over the last several years," John W. Stadtler, president and chairman of National Permanent, said.

In addition, he said, "For whatever reason, S&Ls have been conventional lenders."

To the home buyer, FHA or VA mortgages are generally more desirable than conventional mortgages, which are not insured by the government. This is because at most times, interest rates on FHA or VA mortgages are slightly lower than on conventional loans, offsetting some additional charges - called points - incurred when obtaining an FHA or VA mortgage.

On the other hand, VA mortgages can only be obtained by veterans, and FHA loan amounts are limited to $45,000.