Here is the reason. You can look at the data from 1 or 2 years back of AAPL and MA shares when they were about the same price and they are still the pretty much same. But when you compare everything else the picture points other way around.
Ma EPS: 4% vs APPL EPS 9% P/E Ratio: Ma share cost twice as much as AAPL Net income: MA $1.8 Billion vs AAPL $28 Billion cash in hand: MA $4 Billion vs. AAPL $96 Billion
Based on these facts either MA share should drop to below $250 or AAPL share jump to $800. It means recent run of MA share is nothing but speculation. If you look at the visa shares they jumped only 25% in same period which also tells the share should have jump from $190 to $250 max because of international roll out plans of MA. May be this is the best time to short the MA share and cover it only once MA share reach below $250.