Introduction

"The more you fuck around, the more you find out" i remember reading this quotes from X, that was quite funny, because that's what actually leads me to find out this arbitrage opportunity.

First, get your fees down

This is the boring part and it's also the entire reason any of this worked, so I'm putting it at the top.

If you're paying retail fees you're cooked before you start. It doesn't matter how good your idea is. A 0.045% taker fee eats an arb that a 0.01% taker fee prints on.

What I had going in:

• 0.01% on both maker and taker, which is about as low as it gets
• 75% of that back as rebate, so a million in volume cost me $25 instead of $100
• $25 per active million in volume, but only if you actually hold the position and trade like a real user
• Daily rewards, top 10 by volume got $75 to $100 per account
• VIP program on top, 0.1 bp back per million

You get this from a BD relationship. Not from signing up on the website and hoping. And the thing nobody tells you when you're 25 and broke is that they don't care how much money you have. They care about volume. That's the only KPI. If you can push volume you can get a good deal.

So go find the BD. They're on Twitter. Send the message. The worst thing that happens is nobody replies.

I got mine and then I went looking for something to point it at.

The method

Everyone knows BTC costs the same everywhere. Binance says $94,820, MEXC says $94,825, and that $5 is gone before you've finished reading this sentence. It can't be arbitrage.

Then in 2025 I found Flipster.

They didn't charge a trading fee at all. They took it inside the position as slippage instead. Open a million in volume and you're immediately down $125 before Bitcoin has moved a dollar. Whatever, a fee is a fee.

The interesting part was the quote itself. Their long price and their short price were separated by $20-$25, and it stayed separated. Then ten or fifteen minutes later it would drift back in line with everyone else.

Why? I'll be honest, I have no idea. Their pricing just worked differently from every other venue I'd traded on. I stared at it for a while waiting to find the catch and never found one.

So: long on Flipster, short the same size on MEXC. Wait. Close both when the prices meet.

Equal and opposite legs means Bitcoin can do whatever it wants. Whatever the long loses the short makes back. I'm not betting on price, I'm betting that two numbers describing the same thing stop disagreeing with each other.

Tested it at $500,000 to see if it was real.

$26, ten minutes later. (minus fee and i closed late on one-side)

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Doing it by hand

I don't code. Claude and Codex weren't good enough in early 2025 to write anything I'd trust with real money, and I couldn't have checked their work anyway.

So every single order was manual. Open the long, open the short, sit there, close both. Thirty times a day for two months.

Sixteen hours in front of the screen. I'm not rounding up for the story, that's what it was. I was a college kid who'd just worked out you could make a hundred bucks an hour by clicking a button and watching magic internet money appear, and the adrenaline going through my veins was insane. I'd close a pair, see the number, open the next one immediately. There was no version of me walking away from that screen to do something reasonable like eat.

I didn't waste a minute. Not even to piss.

Not every one worked. Sometimes the gap widened against me instead of closing and I had to eat the loss.

The other reason I never left the chair: I had about $10,000 on each exchange running half a million or more in volume. The pair was neutral so the price itself couldn't kill me, but one leg can still get liquidated on its own if that exchange runs hard before I close both sides. Sitting there wasn't discipline. It was the only thing between me and a forced close on the wrong side.

What actually paid me

Here's the funny part.

Flipster's slippage was $125 a million. Rebates gave back most of it, call it $25 out.

MEXC was around $100 a million in taker fees, minus the 75% rebate, so $25 out.

Then the BD deal paid $25 for every qualifying million. Daily top 10 paid $75 to $100. VIP kicked in more.

Look at those numbers next to the $26.

The price gap was the smallest thing on the page.

I thought I'd found an arbitrage. What I'd actually found was a fee schedule. The gap wasn't the money, it was the excuse. It let me push enormous volume through both venues without ever taking a real directional bet, and the volume is what got paid. Strip out the rebates and every position I opened was a loser.

Then it died

I was never worried about the gap closing. I was worried about the exchange, and the exchange is exactly what got me.

Around July 2025 Flipster changed how they quote and what they charge. 0.04% trading fee, and the gap between their long and short price was gone. Just gone. The trade stopped existing.

Two months. That was the entire run.

What's left

The trade is dead and you can't do it. Fine.

But the reason I found it is still sitting there, and it's not sophisticated at all. I stopped assuming every exchange works the same way. Not the same price. The same way. How they charge you, how they quote, what they pay you to show up.

Everyone in crypto watches the price. Almost nobody reads the fee schedule.

Go read the fee schedule. Go message the BD. Worst case nobody replies and you've lost ten minutes.

This is what happened to me, not a recommendation. The gap is gone, the rules changed, and I have no position at either exchange today.