I have a stupid question: was there a regulatory change in the recent past that made it easier to file for IPOs? Or is this just a coincidence that all these S-1s were filed around the same time?
That sounds a bit hand-wavey / crystal ball / technical analysis, but has reasons in fundamentals: Several years of collective prosperity decrease risk aversion, low inflation / money targets (thus interest rates) make (over) investment cheap (offices, tall buildings, capital stock, etc), collective memory fades.
Certainly not written in stone, however. A book recommendation covering the above, and influence of such fundamentals in long term financial trends: Irrational Exuberance by Robert J Shiller.
How big is your short position?
When others are afraid, be brave, etc...
I think it'll be a fun project to scrape the data and create some visualizations with it. Look out for a Show HN from me if you're interested!
Surprisingly, it doesn't look like the overall number of IPOs is any higher this year than in the past.