The Collaborative International Dictionary of English v.0.48:

Rig \Rig\, v. t.
   To make free with; hence, to steal; to pilfer. [Obs. or
   Prov.] --Tusser.
   [1913 Webster]

   To rig the market (Stock Exchange), to raise or lower
      market prices, as by some fraud or trick. [Cant]
      [1913 Webster]