The US government avoided a shutdown on Sep. 30, which could have contributed to Bitcoin's sharp rally on Oct. 1. The S&P 500 Index has also historically performed well in October. However, a short-term up-move in the cryptocurrency markets is unlikely to start a runaway rally, as the skyrocketing US dollar index could keep the bulls on the edge of their seats. Important overhead resistance levels in Bitcoin and altcoins may attract sellers, so it's essential to keep an eye on market performance and analyze the charts to make informed decisions.