Heritage Auctions latest Sunday Internet Sports Auction featuring 148 lots closes January 4 to initial bidding at 10 PM CT. On a lot-by-lot basis, starting at 10:00 PM CT, any person who has bid on the lot previously may continue to bid on that lot until there are no more bids for 30 minutes. For example, if you bid on a lot during Normal Bidding, you could participate during Extended Bidding for that lot, but not on lots you did not bid on previously.
If a bid was placed at 10:15, the new end time for that lot would become 10:45. If no other bids were placed before 10:45, the lot would close. If you are the high bidder on a lot, changing your bid will not extend the bidding during the 30 Minute Ending phase (only a bid from another bidder will extend bidding).