Walgreen Co said it would buy a 45 percent stake in KKR & Co-backed Alliance Boots for $6.7 billion in a cash and stock deal that would bring together the two largest pharmacy chains in the United States and Europe.

Walgreen, which has the option to buy the rest of Alliance Boots in the next three years, said it would pay $4 billion in cash and 83.4 million shares for the stake.

The combined business would have more than 370 distribution centers delivering to more than 170,000 pharmacies, doctors, health centers and hospitals in 21 countries. It will also be the world's largest buyer of prescription drugs and many other health products.

Private equity firm KKR, which invested $2.45 billion in Alliance Boots in 2007, will receive $2.0 billion in cash and stock and will gain a seat on Walgreen's board.

Walgreen said the deal would add substantially to its earnings per share in the first year.

The company also reported third-quarter earnings of $537 million, or 62 cents per share, compared with $603 million, or 65 cents per share, a year earlier.

Excluding costs related to the Alliance Boots deal, Walgreen earned 63 cents per share.

Analysts on average were expecting earnings of 62 cents per share, according to Thomson Reuters I/B/E/S.

Sales fell 3.4 percent to $17.75 billion, missing analysts' estimates of $17.87 billion.

Walgreen said it would increase its quarterly dividend to 27.5 cents per share from 22.5 cents.

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