Walgreen Co. is expected to begin selling as much as $10 billion in bonds in dollars, euros and British pounds as early as this week, in a sale that would rank among the largest corporate bond deals this year.

The deal would add to this year’s deluge of corporate bond issuance, with U.S. bond sales from highly rated companies like Walgreen expected to be the highest on record this year. Walgreen would also become the latest U.S. company to tap overseas debt markets, following Apple Inc., which earlier this week sold $3.5 billion of debt in euros, its first nondollar bond.

Executives from Walgreen and Alliance Boots were expected to hold investor calls Tuesday and Wednesday. Goldman Sachs, Bank of America Merrill Lynch and Deutsche Bank are helping to arrange the deal. A spokesman for Walgreen declined to comment on the sale.

Investors say the bonds will likely be well received. Other companies have tapped the debt market this week in what has already been a busy few days, including American Express Co. and Noble Energy Inc.

“Given the size of the deal, I imagine they’ll probably come at a nice concession,” said Matthew Duch, portfolio manager at Calvert Investments, meaning the bonds will likely offer relatively high yields compared with the company’s outstanding debt. Mr. Duch’s firm, which oversees more than $13 billion, would be interested in purchasing the bonds, he said.

Last month, Moody’s Investors Service downgraded Walgreen one notch to Baa2, considered investment grade and two notches above junk. The ratings agency said the company’s debt levels will increase from $4.5 billion to between $17 billion and $19 billion following the closing of the Alliance Boots acquisition and a $3 billion share repurchase program.

Walgreen already owned a 45% stake in Alliance Boots, acquired in 2012, and announced in August that it was exercising an option to purchase the remainder of the company. It said it would pay $5.3 billion in cash, and stock valued at about $10 billion, for the remaining portion.

Write to Mike Cherney at mike.cherney@wsj.com


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