I think kevin has nailed it, this is and always has been a sucker yield play which will implode badly eventually, whether six months, a year, eventually.
I bought 2000 shares at $19.60 but have been harvesting losses every year to offset any unforeseen large gains down the road. I thought it would eventually be some preferred I had bought cheap during the bad old days, bit this gain will more than offset the losses. It is a good problem to have, but I would have preferred to roll it into the new owner. I have more cash now than potential investments, so this will just add to the under-earning stash. That's life, and I suspect I will have good opportunities for the cash in the not too distant future.
Odd that's there's no news. This is either confusion with HCP or a concerted short attack. It could also be a leaked share offering coming up. The good news is that the fundamentals are not affected, so this will pass.