** Shares of Ritchie Bros. up 9.2 pct at C$37.96; U.S.-listed shares also jump
** Both stocks rise as much as 12 pct, best day in over 5 months
** Co, which auctions used industrial equipment, posts Q2 revenue of $166.2 mln, beating estimates by $3.5 mln
** Results helped by recently completed acquisition of Caterpillar-backed IronPlanet Holdings Inc
** More than 312,000 Toronto-listed shares traded, 2.2x their 30-day moving avg
** Up to Monday’s close, RBA had fallen 18.7 pct on TSX and 16.8 pct on NYSE this year