The capital was under tight security, with a heavy police presence at venues where President Xi Jinping usually hosts foreign dignitaries, fuelling speculation that Kim was in town.
State media and officials did not confirm whether Kim, or any other top North Korean official, was visiting Beijing after Japanese media reported that a special North Korean train had arrived in the city on Monday.
Authorities deleted or blocked any mention of Kim, North Korea, or the supposed visit on the country's heavily-used social media, even going so far as to bar insulting Chinese nicknames for him.
Kim is often referred to on China's internet by the moniker "Kim Fatty the Third" -- as the third Kim to lead North Korea after his grandfather Kim Il Sung and father Kim Jong Il.
Even variations like "Fatty Fatty Fatty has come", "Fatty Fatty Fatty Beijing" and "he really came" appear to be banned phrases on the Twitter-like Weibo service.
But Chinese investors, who are known for their often bizarre, superstition-based buying choices, sought to make a profit off the rumoured visit.
A Chinese firm called Changbai Mountain Tourism Co. Ltd, which is based in northeastern China, also surged by its 10 percent daily limit in Shanghai. Changbai mountain is a peak along the China-North Korea border.
Another firm called Dongguan Golden Sun Abrasives, a company that makes products like sandpaper, also surged by its 10 percent limit.
"Golden Sun" is seen by some Chinese as referring to Kim.
Other companies whose names contained at least one character from Kim's full name also jumped.
In Shenzhen, Kingsignal Technology, which Chinese name contains the "Jin" character, also surged by its daily 10 percent limit.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)