You just can't let emotions rule your business decisions. This is one of the most common mistakes that stock investors commit: holding on to stock in the hopes that they will go up when the correct action would have been to sell, sometimes even at a loss, to avoid even greater losses.
I think Yang let his emotional attachment to Yahoo! get the better of him. He thought his baby was worth more when it wasn't, and may not only see his company devalued further, but lose shareholder confidence in the process.
There is only one place left for Yang to go after this, and that's downtown.