Sigma filed patents for several different lenses designed for APS-C based DSLR cameras: 18-35mm f/1.8, 15-30mm f/1.8, 17-35mm f/1.8, 16-50mm f/2.8 and 12-24mm f/2.8.
Olympus filed a patent for a 12-150mm f/4-6.3 Micro Four Thirds lens with image stabilization (IS).
