Well, r0ach was right in that Bitcoin, after a big fake-out drop, is rallying smartly: close to $520 as I write. And there definitely is a short-term drop in many alts that corresponds well to BTC's recent pump.

But of course, many of us oldies remember the days when Litecoin shot up faster than Bitcoin - that's the big story undergirding the positive-correlation "leverage" argument.

To be honest, I have no idea whether the correlation between Bitcoin & longstanding big alts is positive, negative, or how said correlation changes with time & market conditions. As far as I know, there's no archive of altcoin raw trading records - there is for Bitcoin - and Coinmarketcap's weekly archive page is too "chunky" to provide a statistically reliable data set.