When you see a huge drop in a coins price, people will sometimes blame it on whales that are dumping on the market. Whales are people or possibly a group of people working together to hold a large percentage of that coin and can use this to their advantage to manipulate the price of a coin to the desired price. Typically when this occurs "weak hands" will start panic selling so they can buy back into the coin at a cheaper price. Not always does his tacit work in the whales favor.