Companies interested in acquiring Santa Anita Park in Southern California and Lone Star Park in Texas from bankrupt Magna Entertainment Corp. had until late Friday to submit detailed bids for the properties, but as of Friday afternoon, the identities of any bidders for the properties could not be confirmed.\nRepresentatives of Magna's bankruptcy advisory firm and its bankruptcy attorneys did not return phone calls. Over the past several weeks, however, officials close to the bidding process have said that they expected four to five expressions of serious interest for each track.\nMagna filed for bankruptcy in early March after posting hundreds of millions of dollars in operating losses over the past six years and going deeper and deeper into debt. At the time of the bankruptcy filing, Magna owed its largest creditor, its parent company MI Developments, $370 million.\nA U.S. bankruptcy court in April approved Magna's plan to auction the two tracks, along with Remington Park in Oklahoma City, Thistledown near Cleveland, and Portland Meadows in Oregon. Under the plan, Magna's bankruptcy advisory firm, Miller Buckfire, will vet the bids that were due on Friday and then provide the identity of the leading bidder for each or all of the properties to the court by Aug. 8.\nIn early September, an auction will be held in New York in which other bidders may challenge the leading bid. Bidders did not necessarily have to have identified themselves by the July 31 deadline to bid in September, but would need to submit financial credentials to Miller Buckfire before the open auction to prove that they could finance the bid.\nSeveral recent developments have affected the value of some of the tracks that are being offered for sale. In California, the owner of Hollywood Park received final zoning approval to redevelop the racetrack property, though there is no clear timetable for when the track will close. When it does, though, Santa Anita can be expected to take over more racing dates on the Southern California circuit.\nIn Ohio, the state legislature passed a budget that authorized 2,500 slot machines at each of the state's seven racetracks, including Thistledown. That authorization, however, is expected to be challenged in court by groups that claim it violated the state's constitution.\nMagna also owns Laurel Park and Pimlico Race Course in Maryland; Gulfstream Park and Palm Meadows training center in Florida; Golden Gate Fields in Northern California; the account-wagering company XpressBet; half of the horse racing television network HorseRacing TV; and the bet-processing company AmTote. Previously, the company said that it would entertain offers for those properties as well.