2019-07 I am not always right

In the last class I mentioned that the stock market reacts only to news. On Wednesday the general expectation was that the FED will reduce the interest rate by 0.25%. This indeed happened.
So: no news = no reaction? Actually, the market did react:

At 2pm, the time of the announcement, stocks jumped up, then fell, then jumped again, then fell even more.
Possible explanations:
- the market actually expected something else
- the expectation was not 100%; once the thing happens, any uncertainty is resolved
- the changes in stock market were quite small. Note that the volume did not change much.