Nordqvist shot a 5-under 67 at the Guadalajara Country Club for a 36-hole total of 9-under 135, leaving her tied with So Yeon Ryu and first-round leader Pornanong Phatlum. Ryu also had a 67 while Phatlum posted a 69.
There were a dozen players within three shots of the lead and the group tied for fourth at 136 included world No. 1 Inbee Park, Gerina Piller and Lexi Thompson, who shot the tournament's low round of 64.
Lizette Salas and 2010 champion I.K. Kim shared seventh place at 137.
Cristie Kerr, last year's winner who was last in the 36-player field after the first round, moved up the leaderboard with a 67 that put her in 27th place at even-par 144.