head south
1. To escape; to vanish or disappear. (Not necessarily in a southerly direction.) Everyone in the gang headed south when they learned that the police had discovered their hideout.
2. To fall or drop; to depreciate; to lose quality or value. (Especially related to finances or stock exchanges.) The company's stock profile continued heading south for the third day in a row today. I used to be a big player in the stock market, but all my investments have headed south lately.
3. To cease working or functioning; to quit, fail, or fall apart. Talks between the labor union and the construction firm headed south yesterday, so it looks like workers will be on strike again soon. My computer is only a month old, and it's already heading south.