Originally posted by following.eric I remember reading about this
As far as I can tell, from looking at the Sigma USA site, Sigma is still selling K-mount lenses - eg the 8-16, two 10-20's, 10-50, 17-70, 18-35, 18-200, 18-250, 18-300, 35 f1.4, 70-300, and a few more. But it is true that they don't have as many lenses for Pentax as for Nikon or Canon mount.
Worth noting that many Sigma lenses - eg the 8-16, or even the 300 f2.8 - seem to drop off from availability for Pentax, only to re-appear again a little while later. Seems Sigma does much of their lens manufacturing in batches, so it's hard to be conclusive about what they are really up to.
Although you can still find Tamron lenses like the 10-24, 17-50 or 90mm macro for K-mount in many stores, Tamron do seem to have over the last few years stopped making K-mount lenses under their own name.