US criminal authorities are gathering information on contacts among dozens of short selling hedge funds and research outfits as they investigate possible trading abuses, according to a firm with first-hand knowledge of the probe.

The Department of Justice has sent subpoenas asking for information about a list of more than two dozen firms to a smaller group of market participants. Among other things, they are asking for calendar information and communications.

The list of names includes some of the best-known firms that publish negative research and funds that seek to profit when individual share prices fall. Among them are Muddy Waters, Melvin Capital, Hindenburg Research and Citron Research. Spokespeople for the firms either declined to comment or did not return phone calls.