My wild guess how this happened, if you are selling your altcoins most probably you will sell it to BTC ,sometimes to ETH. Everytime a trader sells its altcoin, this would push Bitcoin to rise. Thats why, everytime Bitcoin goes down, traders either sell their Bitcoins to USDT or simply buy altcoins.
But the situation Bitcoin falldown, Altcoin rising up in yesterday can't like your mean. Because it's just by small investor hope their altcoin can increasing after breakdown of Bitcoin, but they don't know themselves create trap trend and make market like "recovery".no, that altcoin short rise was because they reached their bottom!
when an altcoin gets dumped very hard, the price drops fast and big, this means a good opportunity to pick up some cheap coins to sell on the recovery. some people call this a dead cat bounce. you wait for the dump to stop and price to reach the bottom and start buying that altcoin, then in about half a day or so you sell as it recovers for a nice little profit.
for example ETH had about 7-8% recovery today which i enjoyed the profit of.
