Based on recent market analysis over the past six months, the three most stable cryptocurrencies to trade are:

1. $BTC :

Bitcoin remains the most stable cryptocurrency due to its large market capitalization and widespread recognition. It serves as a digital store of value, often referred to as "digital gold," and experiences lower volatility compared to many other cryptocurrencies. Its stability is bolstered by high liquidity and robust institutional interest.

2. $ETH :

Ethereum is the second-largest cryptocurrency by market cap and plays a crucial role in the decentralized finance (DeFi) ecosystem. It is known for its smart contract functionality and extensive use in decentralized applications (dApps). Ethereum's stability comes from its strong developer community and continuous upgrades, such as the transition to Ethereum 2.0, which aims to improve scalability and security.

3. $USDC :

USD Coin is a stablecoin that maintains a 1:1 peg to the US dollar. It is used widely in the crypto market for trading, lending, and as a safe haven during periods of high volatility. USDC is known for its transparency and regulatory compliance, providing confidence to traders and investors. Its stability and wide adoption across various blockchain platforms make it a reliable choice for those seeking minimal price fluctuations.

These cryptocurrencies are considered the most stable due to their large market caps, widespread adoption, and lower volatility, making them suitable for trading and investment in a fluctuating market.