can I elect a mark to market election as a day trader

You have to have trader status first:

Special rules apply if you're a trader in securities, in the business of buying and selling securities for your own account. The law considers this to be a trade or business, even though a trader doesn't maintain an inventory and doesn't have customers. To be engaged in business as a trader in securities, you must meet all of the following conditions:

• 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.