Reverse yankee bonds are one of the themes of 2015.

Corporates can borrow at rates 1.5-1.75 percentage points cheaper in Europe than they can in the United States. That difference is attractive enough for US companies -- some with very little or no operations in Europe -- to tap euro-denominated debt markets.

Today, Anheuser-Busch priced 5-15 year bonds in euros in a €3 billion deal. Berkshire Hathaway, Proctor & Gamble and Apple have raised money in euros over the past six months and both said the money would be converted to US dollars to fund US operations or pay dividends.

In 2014, total reverse yankee bond sales were $50 billion but that number has probably already been surpassed so far this year. Chinese companies are also said to be raising money in Europe at a record pace.

German 10-year yields