According to CCN.com;
Signs of Diminishing dominance of Bitcoin
Firstly, Bitcoin (BTC) has had a hard time breaking the $9,000 levels lately. The King of Crypto has been unable to break through past $9k for the last 10 days. At the same time, the total crypto market capitalization has been oscillating between $360 Billion and $408 Billion. The current BTC dominance stands at 37.1% of this market cap. However, when we look at the dominance of Ethereum (ETH), it has increased from 17% in early April, to current levels of 18.55%.
And eth has trouble breaking $1000. Eth is a strong competitor to bitcoin but just because bitcoin may be "struggling" to break some arbitrary number in dollars it doesn't mean ethereum is going to "dethrone" bitcoin.
Secondly, there has been a growing trend of tokens and coins doing double digit gains as Bitcoin (BTC) stagnates or dips further. Once such case is the recent 10% gains of Ox (ZRX), Zilliqa (ZIL), Aelf (ELF) and Ontology (ONT) on May 17th; less than 3 days ago.
Well this is misleading. If some random alt coin worth $0.00001 goes up 10% it's still nothing. Most of the smaller coins are just pump and dump schemes designed to make the creators and early investors rich so these sort of quick gains are not uncommon, but they're not much different from ponzi schemes really.