I had $ 5,000 in a savings account at my local bank that I may not use for awhile?

Last week, I sat down with an asset mgr/stockbroker type person and they said I may want to put that $ 5,000 into a MMMF (money market mutual fund) with check writing privileges so that I it will earn more interest. So I did that........now I wonder ';If the stock market should suddenly go Down, could I lose some of that $ 5,000 ? ';

I am now concerned about losing some of my $ 5,000.... if the stock market does badly.