While stock traders have been piling into the Santa rally, bond investors this holiday season have been busily building what some say could be the biggest short position ever in Treasury futures.

That’s a massive bet that interest rates will rise.

George Goncalves, head of rate strategy at Nomura, calculated some $29 billion worth of shorts across the Treasury futures complex—the highest level, post-financial crisis.

While it’s clear rate expectations are slightly higher for 2015, with the Fed expected to raise rates, Goncalves said the market could be positioning for other events as well, such as European Central Bank easing.

“We’ve got the ECB meeting Jan. 22. The first week of January we get all of the European inflation data. That’s going to really set the tone,” he said. The market sees a chance that the ECB could announce a quantitative easing-stylebond buying program, but weak inflation data would reinforce that notion.