Bitcoin / ETH vs. Traditional Indices

Long-time lurker, first-time poster. My portfolio is a mix of traditional equities and crypto. I'm curious about how others view the correlation (or lack thereof) between assets like $BTC and $ETH versus indices like $SPX and $NDX during periods of market stress or rallies. $BTC is holding its ground today, up slightly, while indices are down. Any seasoned analysts have models they use for this?