Comment by jasonwatkinspdx

It's because reporting requirements changed, in particular employees with stock options no longer counted as shareholders for the purpose of crossing the mandatory reporting threshold.

Before that change companies like MS were in essence forced to IPO, because they'd get all the downsizes of public reporting, without the benefit of accessing market liquidity. So once you were over the threshold, it made no sense to not go all the way.

That's no longer true, and has coincided with a huge expansion in private equity funding growth stage companies vs needing public liquidity. As a result these IPOs being done after their growth stage is largely over are offering the public a very different bet that tech company IPOs of the past.