While Charles Schwab also offers their onw solo 401k plan which tends to me more restrictive, a self-directed solo 401k plan from My Solo 401k Financial may be invested in equities including stock options using a Charles Schwab company retirement account brokerage account. This is possible because you opened a solo 401k with My Solo 401k Financial and Charles Schwab is simply holding the solo 401k funds.
However, the highest level of options trading that may be done inside a self-directed solo 401k brokerage account held with Charles Schwab is level one options. Please CLICK HERE to use the Schwab application to add options trading to your self-directed solo 401k brokerage account.