Plaintiffs in a 2-year-old Houston state court lawsuit against Philadelphia's Duane Morris filed an amended petition on Aug. 8 that ups potential damages in the case to about $764 million, according to Tony Buzbee, who represents the investor group behind the suit.

“A case like this could bankrupt that firm,” Buzbee said of Duane Morris, which ranks 71st among the Am Law 100 with $454 million in gross revenues last year.

The investors' chief allegations are tied to the actions of the late Aubrey McClendon, a fracking pioneer and serial entrepreneur who was CEO of Chesapeake Energy Corp. and then of American Energy-Utica (AEU). McClendon was indicted on bid-rigging allegations in March 2016, and he died the following day in a single-vehicle collision.