depends on which alts we're talking about. but generally a booming Bitcoin takes the whole market up with it
still bitcoin for last couple weeks is steady around ~600$ but most of the alt-coins are going down (excluding occasional pumps and dumps)
I think it's more about alt-coin market which is filled with more and more coins which doesn't get long enough support..
People are just getting confused what to mine or what to support... and how many weeks like that we will see in future...
https://lh4.googleusercontent.com/-gzNj17gZMVA/Uxj4nYOaWKI/AAAAAAAAFF8/9N-zOguP2zE/w1598-h541-no/11.PNG