check with your broker, they may treat the movement of the securities as a sale at market value in the MTM account that would then become the cost basis in the trading account and likely the holding period would start anew.
if this is done it would be the equivalent of selling them in the MTM account and then buying them in the trading account which is permissible.
be careful, the rule for traders regarding investment securities
The securities held for investment must be identified as such in the trader's records on the day he or she acquires them (for example, by holding them in a separate brokerage account).
by the way the conditions to be treated as a trader are:
You must seek to profit from daily market movements in the prices of securities and not from dividends, interest, or capital appreciation;
Your activity must be substantial; and
You must carry on the activity with continuity and regularity.
The following facts and circumstances should be considered in determining if your activity is a securities trading business:
Typical holding periods for securities bought and sold;
The frequency and dollar amount of your trades during the year;
The extent to which you pursue the activity to produce income for a livelihood; and
The amount of time you devote to the activity.
If the nature of your trading activities doesn't qualify as a business, you're considered an investor.
if you don't meet these conditions the IRS would classify you as an investor meaning your MTM election is invalid.
