A half-sister by Medaglia d’Oro to Group 2 winner King of Rome sparked a bidding war that in the end produced Thursday’s $1.1 million sale topper at Keeneland’s September Yearling Sale.

Newmarket-based trainer Paul D’Arcy signed the ticket for the filly on behalf of London surgeon Dr. Karen Sanderson. Consigned by Tom Evans’ Trackside Farm, agent for Liberation Farm, the filly is out of the Forty Niner mare Amizette, and from the family of champion Althea and stakes winners Twining, Ali Oop and Ketoh. Her half-brother, King of Rome, by Montjeu (IRE), won the Group 2 Royal Whip Stakes at Leopardstown in August for trainer Aidan O’Brien.

“We have a great deal of confidence in the future of King of Rome on the track,” Sanderson said. “We feel this is a good purchase because she’s a very fine filly. She walked very well, and there was everything to like about her. We came to buy the best, and we feel we probably bought the best lot of the day.”

Gross receipts on Thursday totaled $40,534,700, down 10.1 percent from the $45,078,500 posted last year. The session average of $151,815 was down 13.4 percent from $175,403 recorded in 2007, while the median of $125,000 was down 16.7 percent from last year’s $150,000. A total of 267 horses were sold this year compared to 257 in 2007.

“It was a very solid sale in light of the current economic climate,” said Geoffrey Russell, Keeneland’s director of sales. “The criterion buyers are using to judge these yearlings is getting tighter and tighter, and there’s very little safety net. The consignors have done an excellent job of tightening up their appraisals. The not sold rate (down 7.4 percent on Thursday) reflects the ability of consignors to adapt to this market.”

Cumulative gross sales for the first four days totaled $204,698,700, down 15.9 percent from $243,290,500 in 2007. Average was down 14.2 percent from $284,883 to $244,562. The median of $180,000 was down 10 percent from $200,000 recorded last year.

Legends Racing purchased the second- and third-highest priced yearlings of the session, paying $700,000 for a Tiznow colt and $625,000 for a colt by Gone West. Consigned by Lane’s End, agent, the Tiznow colt is out of the unraced A.P. Indy mare Indian Snow, a daughter of Grade 1 stakes winner November Snow. The Gone West colt is from the family of Hollywood Prevue Stakes (G3) winner Roll Hennessy Roll and Artax Handicap winner Value Plus. The colt was consigned by Top Line Sales, agent.

There is no sale on Friday, September 12. Selling will resume Saturday, September 13 and continue through Tuesday, September 23. Sessions begin at 10:00 a.m. daily.