Bitcoin vs S&P 500

Bitcoin is the original cryptocurrency with a hard-capped supply of 21 million coins (about 19.85 million already mined as of April 2026). The asset trades 24 hours a day across roughly 50 jurisdictional markets. Total market capitalization in April 2026 is approximately $1.55 trillion at the $78,000 spot price.

SPY tracks the S&P 500, holding roughly 500 large US companies with combined market capitalization of approximately $50 trillion. SPY itself has $560 billion AUM, expense ratio 0.0945 percent. The two assets represent fundamentally different economic claims: bitcoin is a non-yielding scarce digital commodity, while SPY represents fractional ownership in productive US businesses with earnings growth and dividend yields. Despite the different fundamental natures, the two have become increasingly correlated in price action since 2020.

From 2013 to 2019, bitcoin's 90-day rolling correlation with SPY averaged near zero, with monthly readings ranging from -0.4 to 0.4. The asset functioned more like a niche alternative than a risk asset. Bitcoin had its own cycle dynamics (halvings, ICO bubbles, regulatory waves) that produced uncorrelated returns relative to traditional markets.

The 2017 to 2018 cycle illustrated the disconnection: Bitcoin rose from $1,000 to $19,800 in 2017 (1,880 percent), while SPY rose 22 percent. Bitcoin then fell 84 percent through 2018 while SPY fell only 4 percent. The decoupling reflected bitcoin's primarily retail and crypto-native investor base, with limited overlap to traditional equity holders. The asset class was effectively walled off from broader macro dynamics, which kept correlations low and made bitcoin attractive as a portfolio diversifier.

The COVID period broke the historical low-correlation pattern. From March 2020 through 2021, bitcoin's 90-day rolling correlation with SPY rose to 0.5 to 0.7. Both assets responded together to the Fed's zero-rate policy, the fiscal stimulus that boosted retail investor capital, and the broader risk-on regime that lifted long-duration assets across the board.

The drivers of the inflection were structural. First, retail brokerage platforms (Robinhood, Coinbase, Cash App) made bitcoin easily accessible alongside equities, blurring the holder-base distinction. Second, MicroStrategy's August 2020 corporate treasury allocation of $250 million in bitcoin, followed by Tesla's February 2021 $1.5 billion allocation, signaled that public companies would treat bitcoin as a treasury reserve asset. Third, the SEC approved the first US bitcoin futures ETF in October 2021. The combination produced the highest sustained BTC-SPY correlation since the asset class began.