Baseline is 75 bp - and from what I've seen, as are most analyst expectations. I'm assuming that some small % of the market thinks that 50/100 bp is how it'll turn out. An actual announcement of 75bp should result in a small bump in the market, while a 100bp should result in a large downturn.

Source: https://www.cmegroup.com/markets/interest-rates/cme-fedwatch-tool.html?redirect=/trading/interest-rates/countdown-to-fomc.html