The Collaborative International Dictionary of English v.0.48:

Stockbroker \Stock"bro`ker\, n.
   A broker who deals in stocks.
   [1913 Webster]

WordNet (r) 3.0 (2006):

stockbroker
    n 1: an agent in the buying and selling of stocks and bonds

Moby Thesaurus II by Grady Ward, 1.0:

38 Moby Thesaurus words for "stockbroker":
   Realtor, Wall Streeter, bill broker, bond crowd, broker, cambist,
   cotton broker, curb broker, dealer, diamond broker,
   discount broker, estate agent, floor broker, floor trader,
   floorman, furniture broker, grain broker, hotel broker,
   insurance broker, jobber, land broker, money broker, money changer,
   mortgage broker, note broker, odd-lot dealer, pawnbroker, pit man,
   real estate agent, real estate broker, registered representative,
   sharebroker, ship broker, specialist, stock dealer,
   stock-exchange broker, stockjobber, two-dollar broker