If you are not adding more, holding is absolutely the right thing to do, but take a look to to your left and then to your right, you are sitting with many flakey longs who will do absolutely the wrong thing and sell. And the shorts know this because they will psychologically compel them to do the wrong thing. This is steaight out of the manipulators handbook and setting up as a slamdunk long December 15.
Longs will not be able to resist the tax loss sell, driving prices lower. Shorts will cover into this, taking profits. But shorts will cover less than the tax loss sellers, so prices still drift down, forcing more long sales on falling prices. Shorts will continue covering as tax loss selling dries up, reaching equilibrium Dec 15. Then they will keep covering, spiking prices up. This will be called longs "speculating for a better 2016" but it will really be shorts finishing their covering and actually becoming net long. Many ex longs won't be able to get back in after 30 days except at a much higher price so most will be left in dust, and shorts, now net long, will be laughing and waving at them with their old share certificates. Shorts win both ways.