 The U.K. competition regulator is mulling over AstraZeneca Plcs NASDAQ: AZN 39 billion takeover taker of Alexion Pharmaceuticals Inc NASDAQ: ALXN over competition concern. The U.K.s Competition and Markets Authority is starting the first phase of the probe today and said it should wrap it up by 21 July, deciding at that point whether to start a second, more in-depth appraisal of the deal. 