when BTC falls it's a good indicator that the entire market will fall. It's not always the case, but BTC being as powerful as it is, is affecting the market big time. There are currently about 120 billion into BTC which is about half of the entire crypto market capitalization. In that way, when BTC is falling it's a good indicator that other coins will fall as well. In the past we were seeing that coins were moving the opposite direction from BTC but now it's the case that they move along (because BTC has gained again a lot of market dominance). If you see that happening (BTC falling down) you can invest in safe assets such as gold backed coins DigiCoin or even USDT (US dollar tethered cryptocurrency), they are usually quite stable.