New traders get one of the biggest welcome offers with the Polymarket promo code ACTION, unlocking a $50 bonus once you deposit $10 and complete your first qualifying trade. This hands you five times your opening stake to put toward Monday night's MLB card, headlined by the Marlins vs. Nationals (6:45 p.m. ET, FS1) series finale in the nation's capital. Claim the offer below, then stick around for our odds breakdown and pick.
The math tilts hard in your favor here. You fund the account with $10, take a position on any market that interests you, and Polymarket credits $50 in bonus funds to your balance. Very few platforms pay 5x on a double-digit deposit, and the low buy-in keeps your commitment tiny while you get a feel for how one of the top prediction markets operates.
In addition to the Marlins vs. Nationals battle, there's a full day of U.S. Open matches going all throughout the day, highlighted by the primetime matchup featuring two Americans: Martin Damm vs. Frances Tiafoe. College Football Week 1 also kicks off on Thursday, and that begins a run of five straight days of games. Use your new Polymarket bonus on CFB futures and take the ultimate chance to see who will win the CFB Playoff and Heisman Trophy.
Polymarket runs as a CFTC-regulated Designated Contract Market, so it answers to federal derivatives law rather than state sportsbook rules. Prices display in cents from 0 to 100 instead of American odds, meaning a contract at 54 cents implies a 54% chance that outcome hits. You trade against other users, not a house, and you can sell out of a position before the final outcome.
How to Claim the Polymarket Bonus
Setup takes about three minutes on your phone. Keep your ID handy for verification, and the credit lands automatically once your first trade settles.
- Download the Polymarket US app or tap any link on this page to register.
- Tap the referral field and enter the Polymarket promo code ACTION.
- Verify your identity with your full name, date of birth, address, and a government-issued ID.
- Deposit $10 or more and place your first trade.
- Collect your $50 bonus and put it to work on tonight's slate.
Polymarket States: Where You Can Trade
Polymarket accepts traders in every US state except Nevada, where regulators filed a civil enforcement action earlier this year. Arizona, Connecticut, Illinois, Massachusetts, Michigan, Tennessee, and Wisconsin have all pushed back on prediction markets, though those fights sit in federal court rather than shutting off access. Traders must be 18 or older and physically located in an eligible state, and market availability shifts as those cases move.
Marlins vs. Nationals Odds, Preview & Pick
Polymarket prices Marlins vs. Nationals as close to a coin flip. Here is the full board for this one:
First pitch: 6:45 p.m. ET | Where to Watch: FS1 | Venue: Nationals Park – Washington, D.C.
| Market | Miami | Washington |
|---|---|---|
| Moneyline | 51¢ | 49¢ |
| Run line | -1.5 (39¢) | +1.5 (-62¢) |
| Total | Over 8.5 (-53¢) | Under 8.5 (48¢) |
Miami arrives at 69-68 and third in the NL East, fresh off one of the stranger wins of the MLB season. The Marlins trailed 2-0 into the ninth on Sunday, then scored six runs on two hits, capped by Otto Lopez's two-run homer. Washington sits at 65-74 and hands the ball to left-hander Will Dion, who carries a tidy 3.67 ERA and 41 strikeouts across 34 1/3 innings, but all 18 of his appearances came out of the bullpen. Nobody expects length from him, which puts a Nationals staff that posted a 4.60 ERA over its last 10 games on the hook for roughly half the night.
Miami counters with Ryan Gusto, whose 1-3 record and 3.98 ERA undersell how he has thrown lately. He allowed five earned runs across 24 1/3 innings over his last five starts, blanking Boston over 5 2/3 innings on August 26, and held this same Washington lineup scoreless for four innings on August 21. His own workload cap remains the caveat, so both bullpens factor heavily.
The market reflects that read. Miami's run line shortened from -1.5 (+150) at open to -1.5 (+140) even as most tickets landed on Washington, the fingerprint of sharp money moving one direction while the public leans the other.
- Marlins vs. Nationals Pick: Marlins to Win by 1.5 Runs – Yes (40%): Yesterday's loss was a backbreaker for Nationals, and it appears like that will be too much to overcome today. There is a clear mismatch of bullpens, as the Marlins have been one of the more effective ones this season, while the Nats are at the bottom end. Dion gets his first MLB start (not appearance) tonight, and he has allowed six homers in 34 1/3 innings of work. Look for Heriberto Hernandez to be the catalyst for the Marlins and lead them to victory.
If you like our content and picks, grab the Polymarket promo code above, claim your $50 bonus, and take your position before 6:45 p.m. ET.
Polymarket Promo Code ACTION Terms & Conditions
18+ Only. Restrictions and eligibility requirements apply. Not available in all jurisdictions. Trading involves high risk and may result in loss of your entire investment. See polymarket.us/tos for more information. The Polymarket US App serves as an independent software provider and affiliate of Polymarket US and Polymarket Clearing, the CFTC-regulated derivatives exchange and clearing organization. Not available in AZ, IL, MA, MD, MI, MT, NV, OH, and WA.
