There are no mysteries. ABT will split as of the first business day of 2013. If you like to take your gains, sell now and pay your capital gain taxes based on lower rates. Next year, you might have to pay more in taxes, because of higher rates.
I have a friend that works at higher up position at Goldman Sacks and what they hear going around is that in 2013 the capital gains tax will go from 15% now to 21% no higher than that.Thats just me take.