So not only does this mean that bid sniping can not be used very effectively, it also means that the end time of an auction is not fixed, just like a live auction. (thepointsguy.com)
If less than 65 percent of holdings in a particular issue are in the SOMA account at the time of auction, then the entire amount will be available at auction. (newyorkfed.org)
65 percent limit on holdings auctioned - Sixty - five percent of each Treasury security owned by SOMA, and maturing at least two weeks from the current date, will be available for lending each day, unless fewer securities are in the SOMA custody account at the time of auction. (newyorkfed.org)