For Chinese investors with a sense of history, the nation's world-beating equity rally is looking long overdue for a reversal.

The bull market turned 883 days old on Tuesday, topping China's previous record by 56 days, after a 119 percent surge in the Shanghai Composite Index since December 2012. Even if the advance is measured from June 2013—when the gauge narrowly avoided a bear-market drop of 20 percent—it's still the second-longest since Chinese bourses opened for trading in 1990.

The rally's age is concerning in a market notorious for how quickly it can turn from boom to bust: The 194-day average lifespan of Shanghai bull markets is the shortest among the world's 10 biggest bourses and compares with the 1,625-day mean for the Standard & Poor's 500 Index since 1965. While China's official Xinhua News Agency said Tuesday that the rally has further to go, the Shanghai Composite completed its biggest two-day drop in three months today.