Stop-loss or hold?

I bought 133, 941, 2328 and 2318 at the highest level (HSI above 32,000). Now the downward trend have been continuing without any signs of recovery in the near future and all have dropped by more than 50 percent. As a medium-term investor, I have not set stop-loss limits, accumulating a great on-the-book loss.
Facing USA's economic recession and China's continual macro-financial control measures, should I stop loss or continue to hold them?