Azn bought back 2.4B$ in 2010, 4B$ in 2011 and in Jan 2012 reaffirmed and extended their share buy back program.
Azn currently throws off tons of free cash flow. It looks to me Azn is looking to do something with the cash it would have saved from suspending its buy back program, besides the fact it has openly stated in the past it is in an acquiring mode albeit for small to medium deals like the Amy deal (3B$ if you split the cost in half with BMY).
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