The phrase "to surprise the market" means doing something unexpected or unusual that catches the attention of people involved in a particular industry or field. Full definition
Conversely, when a low expectation stock surprises the market with good news, the price can pop. (mastersinvest.com)
The idea that central banks shouldn't surprise markets is based on a false premise, namely that market volatility should be avoided. (alhambrapartners.com)
Central banks around the world surprised markets with a string of unexpected moves in recent weeks. (cnbc.com)