At the beginning of the year, all the chatter was about a structural "rotation" of investor funds out of Treasuries and into the stock market.

However, Russ Certo, who heads up rates sales and trading at Brean Capital, says he was surprised by the "steadfast bullishness" toward bonds as an asset class that came across in conversations with several clients.

"It's very rare in my career of over 20 years that a nucleus of people are all on the same side, bullish," says Certo. "They're always bearish – sometimes there is a consensus view that is bearish, but I rarely find a consensus view that is bullish, particularly on the high end of the range."