 Shares of Redfin Corp. RDFN, -10.61 tumbled 9.6 in midday trading Monday, after the real estate services company said pending home sales plunged 32.1 in October from a year ago, the most since it started keeping records in 2013. The drop off in pending sales comes as deal cancellations jumped to a record 17.9 of home that went under contract, and a record 23.9 of homes for sales experienced a price drop. 