Sharp closed with a bogey on the par-4 18th to drop into the tie for the lead at 9-under 133 at Old American Golf Club. Altomare had a 66, and Knight shot 67. The three leaders are winless on the LPGA Tour.
Knight was a two-time state high school champion at Aledo, just west of Fort Worth.
First-round leader Stephanie Meadow was 8 under, following her opening 63 with a 71.
Ariya Jutanugarn was 6 under after her second straight 68. The 10-time tour winner missed the cut last week in Indianapolis, ending her streak of 56 starts on the tour without missing a cut.