It depends what for. If the horse is bucking in frustration, wanting me to get off, I'd most likely pull one rein to stop them, plus try and ride it through. Usually I won't ride any horse that is the least bit bucky, as I am a chicken being thrown off of my gelding so many times.
But if the horse just jumps as if it is spooked, I will try and ride it through. Of course if the horse bolts, I'd try and stop it. But there is no use in punishing the horse if they were scared, that just teaches them to me more scared. But I suppose not doing anything might teach them it is right to spook, but it's better than an even more scared horse, I suppose.
The only times these didn't work was when I was younger and was taken off guard, and when my horse pulled me under a crab apple tree and I was too tall to really do anything. Another time was when I was riding bareback, pretty much sleeping on the back of a stocky quarter horse (I had a pillow and everything) and he decided to back up because he was spooked, and off I went. xD