Cryptocurrencies have made a big move higher of late, but the Bloomberg Galaxy Crypto Index is bumping up against 600, a level that's been pretty solid overhead resistance for more than one year.It's too early to call it a downtrend, but the crypto market has struggled over the past couple of sessions after hitting 600 earlier this week. For reference's sake, Bitcoin (BTC-USD) makes up 30% of the gauge, and it pushed well above $12K earlier this week before pulling back to the current $11.6K.The Grayscale Bitcoin Trust (GBTC) is up 73% this year, but just 4.9% on a year-over-year basis.Bitcoin - A big move in 2020