Source : Webster's Revised Unabridged Dictionary (1913)

Stockjobber \Stock"job`ber\, n. [Stock + job.]
   One who speculates in stocks for gain; one whose occupation
   is to buy and sell stocks. In England a jobber acts as an
   intermediary between brokers.

Source : WordNet®

stockjobber
     n : one who deals only with brokers or other jobbers