As of October 19, 2025, more than 38,000 BTC, valued at over $4 billion, remain unredeemed in 17,746 Casascius physical bitcoins. These coins, created by Mike Caldwell between 2011 and 2013, contain real bitcoin secured under tamper-evident holograms. Production of these coins ceased in 2013 due to regulatory issues in the U.S. Out of the total minted, 10,193 Casascius coins have been redeemed, releasing 53,213 BTC. The redemption rates for 1 BTC and 5 BTC coins exceed 50%, while the 100 BTC bars have an 87.72% redemption rate. Notably, the rare 500 BTC bar remains unclaimed, and Series 3 silver coins are largely untouched.