Interestingly enough, LTC dropped more than BTC also.
There is a competetion between two (three, four, etc) chains, even with different hash algo. Competetion with consumed power. Today when typical miner spends many kW/h, he hasa choice whether to run bitcoin or other algo miner. And his power source is limited.
So one chain begin to entice miners from another one along with other chain security. So one chain "eats" others power and security.
This is not like gold and silver live in nature. Gold doesn't destroy silver with just self-existence.
So I may say, Only one chain price has a market value. Other's value is ZERO.