Stop us if you’ve heard this one before: After years of bond- and money-market fund inflows and equity-fund outflows, investors grow fearful of a rebound in yields and the potential for capital losses in fixed-income, sparking a “great rotation” out of bonds and into equities.

That scenario, which implies the potential for a final, euphoric surge to what’s often been described as the “most hated” bull market in stock-market history, has been regularly predicted ever since the 2013 “taper tantrum” that drove a temporary spike in Treasury and other bond yields. Indeed, such predictions are now usually met with derision, acknowledged Julian Emanuel, chief equity and derivatives strategist at BTIG, in a Wednesday note.

Read: Where will the S&P 500 go in 2020? Here are the most bullish and bearish strategists^[1]

But such a phenomenon has marked the “late innings” of “all great bull markets,” he argued. And the current run-up from the March 2009 low is unlikely to be an exception.

“After almost 11 years of equity market rally off the 2009 low, it is futile not to call this a ‘great bull market’. It is,” Emanuel wrote. “And the public will ‘fall in love’ with stocks once more — potentially sending prices materially higher from these already ‘commanding heights’ — before the bull market ends.”

Stocks have indeed soared despite equity fund outflows. The S&P 500 SPX, +0.29%^[2]  rallied more than 28% last year for its best performance since 2013, while the Dow Jones Industrial Average DJIA, +0.60%^[3]  rose more than 22% for its best year since 2017. Over the last decade, the Nasdaq Composite provided a total return, including reinvested dividends, of 347%, according to Deutsche Bank, while the S&P 500 returned 256%.

Need to Know: Irrational exuberance? Why last year’s stellar returns may have been a reversal of ‘excessive pessimism’^[4]

Meanwhile, individual investors did put money into equity funds in the week ended Dec. 26, but that was only the third weekly inflow^[5] since late in the second quarter of 2017, according to data from EPFR.

Emanuel noted that the public remained a huge buyer of bonds and a steady seller of equities over the latter half of the last decade as money-market balances rose to levels seen only during the worst days of the 2007-09 financial crisis (see charts below)....

So what would finally bring a long-awaited fund-flow inflection to bear? Emanuel said two, discrete catalysts would provide the signal.The first would occur if global long-term yields broke above “round numbers,”