This was after the index dropped by 64.89 points on Monday.
The numbers correspond to 4 June 1989, the date of the crackdown against protesters at Beijing's Tiananmen Square.
China strictly prohibits references to the crackdown and has also censored other terms relating to the unrest.
A search for "Shanghai Composite Index" on Weibo, the Chinese version of Twitter resulted in the message: "According to the relevant laws, regulations and policies, the results for this search term cannot be displayed".
The correlation was not limited to just the drop in the stock index.
The market opened at 2,346.98 points, with many bloggers deciphering the 23 as referring to the 23rd anniversary of the crackdown and the rest of the numbers, 46.98, again forming the date of the crackdown, when rearranged.
"Whoa, these figures are too freaky! Very cool," one of the bloggers was quoted as saying by the Reuters news agency.
It quoted another blogger as saying that "the opening figure and the drop are both too creepy".
The army shot dead hundreds of civilians rallying for democracy during the crackdown.
China has blocked access to the term "Shanghai Composite Index" on some of the country's most popular microblogging sites.