A group led by Marvin Davis said it lowered its stake in Los Angeles-based Aaron Spelling Productions to 1.2% of the common shares outstanding . . . Manufacturers Hanover Corp. said it has received approval from the Federal Reserve Board to establish a full-service institutional brokerage operation, including the authority to provide investment advice along with executing trades . . . Kane Miller Corp. of Tarrytown, N.Y., raised its stake in Los Angeles-based Postal Instant Press to 18%.