Citicorp, Nynex and RCA announced the formation of a jointly owned company that will conduct research and development in interactive electronic services . . . Cupertino, Calif.-based Tandem Computers said it has acquired a 19.5% equity stake in Integrated Technology, a telecommunications company in Plano, Tex. . . . Security Pacific Corp. and Hoare Govett Ltd. announced that Security Pacific's London-based subsidiary, Security Pacific Ltd., has been renamed Security Pacific Hoare Govett Ltd. . . . Dayton Hudson, parent of Mervyn's and Target stores, increased its quarterly dividend to 21 cents a share from 20.5 cents, payable March 10 to shareholders of record Feb. 25 . . . Postal Instant Press of Los Angeles said that it expects net income for the third quarter ending March 31 will be about the same as what it reported for the same period a year earlier.