She finished at 18-under 266. Gerina Piller closed with a 64 and was one shot behind. Third-round leader Lizette Salas parred the first six holes and shot a 70.
Thompson caught Salas with birdies on Nos. 1, 4, 5 and 7. Piller made five birdies on the front nine, and a birdie at No. 8 briefly tied her for the lead with Thompson and Salas.