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the MTM under 475(f) is a choice not a requirement. the basic difference is without it your trading gains and losses are reported on schedule D and subject to the wash sale and net capital loss rules. With a proper election, since open positions are MTM at the end of the year, unrealized gains and loss are reported for that year. however rather than being capital gains and losses they are ordinary gains and losses reported on form 4797 line 10. With MTM there are no wash sales to deal with. 

if 2024 was your first year trading it's probably too late to make the MTM election since you had to positively affirm this within 2 1/2 months of your start of trading by placing a statement with your trading records.  you may also be too late to make the election for 2025 because if you started trading in 2024 then the election for 2025 had to be timely filed with your return or extension by 4/15/2025.

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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 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.
If the nature of your trading activities doesn't qualify as a business, you're considered an investor and not a trader. It doesn't matter whether you call yourself a trader or a day trader, you're an investor. A taxpayer may be a trader in some securities and may hold other securities for investment. The special rules for traders don't apply to those securities held for investment. A trader must keep detailed records to distinguish the securities held for investment from the securities in the trading business. 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).
Traders report their business expenses on Schedule C (Form 1040 or 1040-SR), Profit or Loss from Business (Sole Proprietorship). Commissions and other costs of acquiring or disposing of securities aren't deductible but must be used to figure gain or loss upon disposition of the securities. See Topic No. 703, Basis of Assets. Gains and losses from selling securities from being a trader aren't subject to self-employment tax.
If a trader doesn't make a valid mark-to-market election under section 475(f), then he or she must treat the gains and losses from sales of securities as capital gains and losses and report the sales on Schedule D/ Form 8949 as appropriate. The rules and limitations on capital losses and the wash sales apply.
That you are making an election under section 475(f)(1) or (f)(2) of the Internal Revenue Code.

The election statement must have included the following information.

first tax year for which the election is effective.
The trade or business for which you are making the election.

If your method of accounting for is inconsistent with the mark-to-market election, you must change your method of accounting for securities under Revenue Proce-dure 2023-24 (or its successor), available at IRS.gov/irb/2023-28_IRB#REV-PROC-2023-24. Revenue Procedure 2023-24 requires you to file Form 3115, Application for Change in Accounting Method. Follow its instructions. Enter “64” on line 1a of the Form 3115.

Once you make the election, it will apply to the election year and all later tax years, unless you get permission from the IRS to revoke it. The effect of making the election is described under Mark-to-market election made (PUB 550), earlier.
If you want to revoke a prior mark-to-market election within the 5 taxable years ending with the year of change for the election, you must follow the non-automatic change procedures in Revenue Procedure 2015-13 and Revenue Procedure 2023-24, section 24.02(9).
For more information on this election, see Revenue Procedure 99-17, on page 52 of Internal Revenue Bulletin 1999-7 at IRS.gov/pub/irs-irbs/irb99-07.pd