We have seen it in the past, when money coming in to Bitcoin, Bitcoin dominance increases, but then it spreads out into altcoins and Bitcoin either stalls or pull back. That is likely what is going on right now. This is a comparison between Bitcoin, Others (Outside Top 10) and Theta (hourly candles)
Comment: As you can see, everything is up except Bitcoin which is down during the last 5 hours. Is this a trend change? Too early to tell, but if it is, we could expect a massive rally in the alts.
Happy investing/trading!