A stock market bubble occurs when the prices of stocks are driven up well beyond their rational value. We inflate the bubble by pushing too much money in. Eventually the extent of the overvaluation becomes absurd and a correction occurs. The bubble bursts. 

When the MSM (the legacy news organizations that are no longer in the news business) decided they were in the narrative rather than the reporting business, facts became secondary (or totally irrelevant) to the message. They created a propaganda bubble. A bubble inflated by lies and fabrications. 

The inflation of the bubble began slowly. The case of Dan Rather is an infamous example. In 2004 Rather did a 60 Minutes feature impugning President George W. Bush's National Guard service. It was done just 2 months before the election and was clearly intended to influence the outcome of the election. It was that year's "October surprise." 

The program was based on 4 memos allegedly written between 1972 and 1973. There was just one problem: the memos were fabrications. They had been written by computer software that wasn't available in the 70s, and internet sleuths were able to prove it. The whole 60 Minutes piece was a lie. When confronted with this inconvenient truth, Rather famously said that the story was "fake but accurate." 

"Fake but accurate" is actually a fairly good definition of the propaganda the MSM is in the business of peddling these days. The facts are all wrong, but the narrative is correct – that is the narrative is sending the intended message.