Before the year started, most bond market experts predicted yields would rise, as the economy gained momentum and the Federal Reserve continued to reduce its monetary stimulus.

Instead, yields have fallen, with the 10-year Treasury yield dropping to an 11-month low of 2.4 percent last Thursday from 3.04 percent Dec. 31. The yield rebounded to 2.58 percent late Tuesday.

So what happened?

Editor’s Note: Retire 10 Years Earlier With These 4 Stocks

"The market misread the Fed and the economy last year," Robert Tipp, chief investment strategist at Prudential Fixed Income, told CNBC.

"Investors mistakenly assumed once again that any change from the Fed on the QE [quantitative easing] side was going to signal imminent rate hikes and a big bear market in bonds," he noted.

"That was wrong in 2009 and it was wrong every other time since then up to and including the selloff in 2013."

The Fed has reduced its monthly bond purchases to $45 billion from $85 billion last year, but many economists don't expect it to raise short-term interest rates until the second half of next year.

"From a global fixed-income investor's standpoint, there are a lot of attractive opportunities out there," Tipp said.

"Things are nowhere near as cheap as they were [at times] over the last half-dozen years. Nonetheless, . . . you're likely to continue to see outperformance from high-yield and long-term, investment-grade corporates."

Tipp also likes municipal bonds, collateralized mortgage-backed securities and some emerging market debt.

Meanwhile, predicting the bond market's direction has been ever-more tricky, even for the pros.

Bloomberg News reports that Federal Reserve Bank of New York researchers have revamped an index of relative yields on Treasurys, discarding three decades of data that incorporated estimates for market rates from professional forecasters.

“The world’s gotten more complicated and it’s a little different,” James Evans, a New York-based money manager at Brown Brothers Harriman & Co., which oversees $30 billion, told Bloomberg.

“As far as predicting direction up and down, I don’t think they have much value,” referring to bond-market models used by forecasters.

Editor’s Note: Retire 10 Years Earlier With These 4 Stocks

Related Stories:

• Bond Market's Message to Fed: Your 4 Percent Rate Forecast Is Too High
• Unstoppable $100 Trillion Bond Market Renders Models Useless