The Securities Investor Protection Corp. took over the Toledo brokerage firm of Bell & Beckwith yesterday and began unraveling the biggest stockbroker failure in SIPC's history.

The investor protection corporation, which insures stock market investments in the same way the Federal Deposit Insurance Corp. protects bank accounts, could be forced to pay back $36 million to Bell & Beckwith clients as a result of the firm's collapse. The biggest previous brokerage failure, the closing of Stix & Co. of St. Louis in 1981, cost SIPC $26 million.

U.S. District Court Judge Nicholas Walinksi in Toledo yesterday appointed a SIPC trustee to liquidate Bell & Beckwith, after lawyers for the firm Thursday night agreed not to fight fraud charges filed by the Securities and Exchange Commission.

SEC officials said the stock fraud charges were filed a week ago after an SEC audit on an unrelated matter turned up a multi-million-dollar shortage in the account of the wife of Bell & Beckwith's managing partner, Edward P. Wolfram Jr.

The Federal Bureau of Investigation entered the case on Wednesday, but no criminal charges have been filed. Neither Wolfram nor Bell & Beckwith's lawyers have issued any comment on the investigation.

SEC investigators say Bell & Beckwith's books showed that Mrs. Zula J. Wolfram owned stock supposedly valued at $388 million, but SEC auditors found her investments were worth only about $5 million and she owed the firm $46 million.

SEC investigators said the records showed Mrs. Wolfram had stock in a Japanese company valued at $278 million, but the shares were actually worth no more than $5,000. The SEC also found that another $100 million worth of stock that Mrs. Wolfram was supposed to have deposited in a Nevada bank, wasn't there, investigators said.

The shortage in Mrs. Wolfram's account left the old-line Ohio brokerage firm with debts of $41 million and only $5 million in assets--a $36 million deficit, the SEC said.

If SIPC has to pick up the entire $36 million, the insurance agency's protection fund could be depleted to the point that other stockbrokers would have to pay higher fees for SIPC coverage.

SIPC has a $172 million insurance fund, but is required to increase its insurance fees any time the fund falls below $150 million. All brokers will have to pay an additional fee of 0.25 percent of their annual gross revenues to SIPC until the fund is rebuilt.

Neither SIPC nor the SEC has disclosed the names of Bell & Beckwith's creditors, which could include firms not protected by SIPC insurance. The protection agency reimburses customers who lose money when a brokerage house fails, paying up to $100,000 in cash and another $400,000 in securities.

Government investigators so far have offered no explanation of how the conservative little Ohio brokerage firm got so far in debt. Besides its headquarters office in Toldeo, Bell & Beckwith had branches in Lima, Defiance and Finley, Ohio.

All the offices were closed on Monday after a series of unusual weekend court proceedings. Saying they had found a $26 million shortage at Bell & Beckwith, SEC attorneys filed a lawsuit against the firm and asked for a court order to temporarily halt its operations. At an unusual Saturday court hearing, SEC investigators raised their estimate of the loss to $36 million and persuaded Judge Walinksi to order the firm to cease doing business temporarily.

Yesterday, Walinksi made the shutdown permanent and named a Toldeo attorney as trustee to oversee the liquidation.

Earlier in the week, attorneys for the firm said they hoped to find another investment broker to buy Bell & Beckwith, but that effort apparently failed. On Thursday night, Bell & Beckwith negotiated a settlement with the SEC and SIPC. The firm agreed to let SIPC take over its business and signed a consent order acknowledging SEC charges that it had violated federal securities laws.