The special counsel investigating House Speaker Jim Wright has subpoenaed rec-ords on work his wife, Betty, did for a partnership between Wright and a Fort Worth real estate developer and investor, according to a source familiar with the case.

The source, speaking on the condition of anonymity, said investigators for outside special counsel Richard J. Phelan had subpoenaed and received records of transactions, working papers and memos related to Mrs. Wright's work for George A. Mallick.Until 1984, Mrs. Wright was paid $18,000 a year for advice that she gave to an investment venture formed by the Texas congressman, Mallick and their wives in 1979, according to financial disclosure statements filed by the speaker.

With the six-month ethics probe of Wright entering its home stretch, the investigators are examining transactions underlying the partnership company, Mallightco, in much greater detail than available in public records, the source said.

Wright's financial disclosure form shows that he apparently exchanged stock worth between $50,000 and $100,000 for his initial share of the partnership, which was formed to manage investments in stocks, real estate and precious and semi-precious stones.

He listed the value of his Mallightco holdings, which were later placed into a blind trust, at between $100,000 and $250,000. The trustee disclosed last July, two months after the ethics probe began, that the assets had been disposed of.

Wright's investments with Mallick are not mentioned in the six-count resolution, which spells out the bounds of the investigation by the ethics panel, formally known as the House Committee on Standards of Official Conduct.