LOS ANGELES (MarketWatch) -- In what may have been a bizarre coincidence, Monday's opening level and daily loss for China's benchmark Shanghai Composite Index SHCOMP, -0.19% spelled out the date of the crackdown on pro-democracy protesters in Beijing's Tiananmen Square -- on the 23rd anniversary of the incident. The index fell by 64.89 points, matching the 6/4/89 date of the event, which is known in Chinese as the "6-4 Incident." The Shanghai Composite's opening level, meanwhile, was 2,346.98, the last four digits of which contain the fateful date backwards. The strange congruence of the numbers didn't go unnoticed, creating chatter on the Internet and prompting Chinese censors to block all microblogs referencing the Shanghai stock market, according to a Reuters report Tuesday. "Were the 'Ghosts' active in the Shanghai market? ... Just a thought," wrote Piper Jaffray analyst Andrew Sullivan.