Small investors are piling back into the cryptocurrency market, helping drive prices higher even as traders face uncertainty over proposed tax regulations in Washington.

Cryptocurrencies such as bitcoin, ether, dogecoin and other altcoins have rebounded in recent weeks from their midyear pullback, returning to levels not seen in months. Bitcoin on 13 August traded at $47,544, its highest close since May 15, giving it a 64% gain for the year. Rival currency ether is up 344% for the year, while dogecoin — the joke cryptocurrency beloved by retail investors — traded at 28 cents, up more than 5,500% for the year.