The Keeneland September yearling auction -- also known as the biggest Thoroughbred sale on earth -- closed out its 14-session run Monday afternoon with gross revenue of $384,349,900 for the 3,545 hips sold. Both figures were world records. The gross increased 18.3% from the former mark of $324,904,300, set during last year's September sale. The number sold rose 5.2% from the former September record of 3,370 set in 2004 while surpassing the previous industry high of 3,461 for the 1999 Keeneland November breeding stock sale.The average price of $108,420 and the median price of $40,000 both were September peaks, breaking last year's marks. The average advanced 12.5%, from $96,411. The median grew 8.1% from $37,000."The sale dynamics of the yearling market have changed in the last several years," said Geoffrey Russell, Keeneland's director of sales. "The September sale is now the important sale in North America, if not in the world. People come here from all over North America and around the world to buy horses."A Storm Cat – Tranquility Lake colt brought $9.7 million to set a September sale record while becoming the third most expensive Thoroughbred in history to sell at public auction. Forty horses brought $1 million apiece or more, another world record that beat the 39 sold at the 2000 Keeneland November breeding stock sale. The previous record for the September auction was 28 in 2000, and the former mark for a yearling sale was 33 during the 1984 Keeneland July select yearling sale.The buy-back rate for this year's September sale was 21.4%, which was down from last year's rate of 22.7%.Most of the seven-figure fireworks came during the select sessions, when the Maktoum brothers of Dubai and Coolmore Stud battled for top stock. The big prices that resulted "gave confidence to the rest of the market," Russell said. "People thought if the two biggest buyers and the world can do this, then I can (step up my spending), too."Taylor Made Sales Agency's gross revenue of $60,997,400 was a world record for a consignor at a Thoroughbred auction. Taylor Made sold 360 horses.The sale lost some steam as it approached the wire, but was so far ahead of last year's pace that positive results overall were assured. During Monday's final session, 154 yearlings were sold for a gross of $1,325,300, an average of $8,606, and a median of $5,850. The number sold, gross, and average were up from last year's comparable figures of 136, $1,160,500, and $8,533. The median was down from last year, when it was $6,000.An Allen's Prospect -- Cruella colt was the most expensive horse sold during the final session, bringing $50,000. Jonathan Dean bought him from Hidden Haven Farm."As one consignor told me today, 'I hate to see it end,'" Russell said. "But all good things must come to an end."