When it is going up, it is usually because short sellers are covering and folks are buying with NEW money. And when the split happens then, the short sellers pretty much go bankrupt as astronomically more new money comes in.
When splits happen as stock is going down, that means insiders realize that there is a lot more selling going on (or is planned to) and not enough buying, and they need to find a way to get dumb money to buy the stock that they are trying to dump at the highest possible price. Psychologically, they think people will buy Apple if it appears cheaper.
This is not a short influenced stock. There is only 18m short, less than a days avg volume. IF they announce a 10-1 split, which I highly doubt, the stock will add a couple of percent due to the probability that it will be added to the Dow which will cause a lot of funds to have to buy them.