As long as BTC is stable or rises, it says it will be followed by the altcoin, but if it happens otherwise, I will find a reduction, technical and fundamental which is very useful to determine it.
Altcoins are just following bitcoin's move so whenever it goes up, they will too.
I noticed a few weeks ago , the price of some coins is pumped on weekend , but only big coins, like BTC, ETH and BCH , so I also don't know whether the pump is intentional or accidental
I've noticed that too before and I can't find any relevant reason why it happens. Taking a look at the market now, its not only those well known coins but its most of the coins now.