fomo perps: the builder fee, measured

What a builder fee is

Perpetual futures ("perps") are leveraged bets on a price that never expire. fomo does not run its own perps exchange: it sends your orders to Hyperliquid and attaches a builder code, which tells Hyperliquid to add a fee for fomo to each fill. fomo's help centre says it charges "up to 0.05%" of position size per trade, so when you open and again when you close. Hyperliquid's own trading fee is separate and comes on top.

Because Hyperliquid publishes a file of every fill that carried a builder code, one per day, we can add up what fomo's code actually charged: builder fee ÷ notional (price × size), across every fill.

The rate, by month

Every month sits a little under 0.05%. The fee on a fill is either exactly 0.05% or one of a few lower levels, never more: across all 151 days of files, no fill paid above 0.05%.

Who pays less, and how much less

Almost every account pays one level on all of its fills. In the published files for the last 30 days, 99.2% of account-days paid exactly 0.05%. About 0.5% paid 0.01%, but those accounts traded heavily, so they carry 16% of all notional and pull the average down.

fomo does not publish a lower perps rate or say who gets one, so we cannot tell you why these accounts pay less, and we do not name any account. For a typical account, the measured answer is the top of fomo's range: 0.05% per fill.

By fill size

There is no small-trade floor on perps: small fills pay the closest to 0.05%. The lower average on large fills comes from the 0.01% accounts, who trade large.

What it means for one trade

Schedule arithmetic, not a measurement: at 0.05%, the rate almost every account pays, opening and closing a $1,000 position pays fomo $1.00 in builder fees, whatever the leverage, because the fee is on position size, not margin. Add Hyperliquid's own fee on both sides, and funding while the position is open. The fee calculator has the full perps cost.

Perps are not available to US persons under fomo's terms. Leverage can wipe out a position quickly.

Checking the files against DefiLlama

Since September 22, 2026, most daily fill files stop at about 12:10 UTC, so they are a large sample of each day, not the whole day. We use the files for the rate and for shares, and take every dollar total from DefiLlama: fill counts, notional and fees summed from the files are a sample and are never presented as full days. Over the last 30 file-days a file covered 13.5 hours on average; 1 of them covered the whole day.

On the 93 days where a file does cover the whole day, the two sources agree closely: a median difference of 0.41%, and within 1% on 54 days. But the files are never much lower and sometimes much higher: summed over those days they show $1.44M against DefiLlama's $1.37M, and on 10 days the files are more than 10% above DefiLlama. That fits a second gap: Hyperliquid's own counter shows $4.47M of builder rewards all time, $499K more than DefiLlama's total. Some of DefiLlama's days look incomplete; we cannot confirm that this explains all of it.

Day by day

Basis points (bps) appear in the data tables only: 100 bps = 1%, so 0.05% = 5 bps. Every day, with the hours each file covers, is in the dataset.

Method

• Source: Hyperliquid's public builder-fill files for fomo's builder address 0x2a2b6b093a9813fbd8cddae800c3d17d46460d17 (Hyperliquid referral code FOMOFAMILY), one file per UTC day since 2026-06-11.
• Effective rate = sum of builder_fee ÷ sum of price × size, over every fill in the last 30 days with a file. Monthly rates use the files for that month.
• Accounts are grouped by the rate their own fills paid that day; an "account-day" is one account active on one day. No address is published.
• Totals (fees per day and per month) are DefiLlama's. Hyperliquid's builder reward counter comes from its info API.
• We download each day's file once and keep a small daily summary; only new days are fetched.

Caveats

• Recent files cover about half of each day (00:00 to 12:10 UTC). If the second half of the day trades at a different mix of accounts, the true daily rate could differ slightly from the measured one.
• A second, much smaller Hyperliquid builder address is filed by DefiLlama as "fomo Spot" and "fomo Outcome". We have not verified who owns it, so it is left out.
• Whether fomo pays referral shares on perps fees is not documented; DefiLlama records none.