O.K. - don't intend to get into a lengthy discussion around the meaning of "tanking" ... I admit, there are lots of definitions depending on the context, and I agree that many of them sound more serious than what I had in mind:
what I found as meaning of "tanking" after a brief Google search:
1) to put or keep in a tank
2) to move like a tank, esp heavily and rapidly
3) to defeat heavily
4) to fail, esp commercially
5) to fail intentionally (part in sports)
6) A security, sector or market is said to "be tanking" while it is on its way down (from Investopedia).
What I had in mind was definition number 6 ... OHE is going down for the last couple of weeks - and nearly back to its IPO price.
However (not just) in the spirit of the season more than happy to see you replacing the verb "tanking" with another verb which (in your view) better describes the price trend. Any proposals?