You may not be aware of the option, but some companies have the Personal Choice Retirement Account (or PCRA), which works in the same way as your 401K, but let you manage funds yourself. Everything within the PCRA account works like a brokerage account, except for the tax and withdrawal portions.
Once you have your funds in the PCRA account, you can trade securities, any securities just like a brokerage account; your gains would not be taxed and you cannot withdraw without penalties, just like a 401K.
Since this is very risky, that's why the option is not mentioned or offered to most people. I urge you to speak to a financial adviser prior to making any changes or attempting to manage your 401K yourself.
Cheers,