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Why did Robinhood Chain’s L2 base fee rise so sharply?

This report uses onchain data to follow L2 gas use through Robinhood Chain’s Nitro pricing mechanism as the L2 base fee rose.

AuthorsMoAliTom
Updated 7 September 2026 · v1.3
Fixed report, not updated on a schedule. Activity data begins 1 July; parameter history runs from genesis through 6 September 2026.
Robinhood Chain under load

Robinhood Chain’s fee surge outpaced its transaction growth.

Robinhood Chain runs Nitro and ArbOS as an Arbitrum Dedicated Blockchain. That architecture separates the L2 execution price studied here from Ethereum L1 gas and Robinhood Chain’s L1 data fee. Robinhood Chain can set its own minimum base fee, target rates, and adjustment windows within Nitro’s multi-constraint pricing model.

The pricing mechanism keeps L2 gas use within the capacity its infrastructure can sustain over different periods. Backlogs let it react to short spikes and keep track of load that lasts longer. Arbitrum’s multi-constraint pricing research explains why it uses several targets and windows instead of one combined constraint.

Transaction volume rose modestly across the comparison weeks, while L2 gas used rose much faster. The report looks at the fee move, the contracts that consumed the gas, and the backlog that carried excess demand from one block to the next.

Scope: This is a descriptive reconstruction, not a correlation study or causal estimate. It reports observed findings and uses Robinhood Chain’s pricing rules to explain the fee path.

Robinhood Chain metrics · arbdata.comRobinhood Chain docsOnchain explorerNitro sourceWhy multi-constraint pricing?Nitro whitepaper

Executive Summary

Question: Why did Robinhood Chain’s L2 base fee rise much faster than its transaction count?

  • Transactions grew, but L2 gas used grew faster. Across the two comparison weeks, transactions rose 7.5% while L2 gas used rose 63.0%.
  • Gas use became concentrated. The top 3 destination contract addresses accounted for 47.7% of recent L2 gas used; the top 10 accounted for 63.8%.
  • Persistent demand created sustained backlog pressure. When blocks used more L2 gas than the chain could clear at its configured rate, the excess carried over. The pricing formula turns that accumulated backlog into a higher shared base fee.

L2 gas-used measure: We calculate max(gas_used − gas_used_for_l1, 0) from transaction receipts. This is the transaction receipt’s gas used after removing the L1 poster-gas equivalent. It is not a CPU-only or multigas computation measure.

What rose faster: activity or fees?

Activity climbed, but fees broke away from the transaction trend. Daily transaction volume stayed elevated through the summer. Robinhood Chain’s L2 gas price and average transaction fee then rose much faster in late August. That gap tells us to look at how much L2 gas each transaction used and how long the load persisted. Transaction count alone is not enough.

Data window: 1 July to 6 September 2026. See Robinhood Chain Blockspace on arbdata.com. Daily values come from Robinhood Chain transactions. USD fees use the daily ETH/USD price. The fee card provides outcome context; it is not an input to the pricing replay.

Which contracts concentrated the new L2 gas use?

Transactions tell us how often the chain was used; L2 gas used tells us how much gas those transactions consumed on Robinhood Chain. We compare L2 gas used by destination contract address across two equal seven-day windows: 24–30 August and 31 August–6 September. We calculate it from onchain transaction receipts as max(gas_used − gas_used_for_l1, 0). This is the transaction receipt’s gas used after removing the L1 poster-gas equivalent. It is not Nitro’s narrower multigas computation resource. Dates are UTC and block ranges are inclusive.

63.0%more L2 gas used24–30 Aug · blocks 44,418,352–50,419,085 · 14.65 Tgas
31 Aug–6 Sep · blocks 50,419,086–56,389,056 · 23.88 Tgas
7.5%more transactions24–30 Aug · blocks 44,418,352–50,419,085 · 80.0M
31 Aug–6 Sep · blocks 50,419,086–56,389,056 · 86.0M
63.8%of recent L2 gas used31 Aug–6 Sep · blocks 50,419,086–56,389,056
Top 10 destination contract addresses

L2 gas-used concentration

Share of L2 gas used, 31 August–6 September.

L2 gas used by destination contract address

Grouped bars compare the top 10 contract addresses plus the rest of the chain before and during the pressure period.

What activity did the busiest contract addresses handle?

The increase was concentrated in trading and execution infrastructure. Relay-style multicalls and GMGN swaps were the two largest contributors, while ERC-4337 EntryPoints batched smart-account operations. Two of the top three addresses map directly to routed trading. The third is general-purpose smart-account infrastructure. Axiom, OKX and Uniswap also routed trades across liquidity venues. Pons was different: its launchAndBuy call creates a token and curve, then performs an initial purchase, making each transaction use more L2 gas.

The Fomo app was part of the same Robinhood Chain trading wave. Fomo announced Robinhood Chain support and later highlighted trading in PONS and CASHCAT. Relay Protocol linked Fomo’s Robinhood Chain experience to Relay infrastructure. This makes Fomo relevant to the leading Relay-style destination, but the data cannot isolate Fomo users or measure Fomo’s share of Relay traffic. It also cannot show that every Relay call was a memecoin trade. The GMGN link is more direct: GMGN describes its Robinhood Chain product as a memecoin discovery and trading terminal. A router may serve several interfaces, bots or end users. Its address shows what was executed, but not which front end sent the user there. The unverified router remains unlabeled because its ABI is not public.

ContractDominant methodPressure-period gasIncreaseShare of net increaseGas / txObserved role
GMGN router0x65050a9b…262c40dcswap4.799 Tgas+3.531 Tgas38.3%410 KgasRoutes token swaps across one or more pools for GMGN users.
Relay multicall router0xccc88a9d…f1c315bepermit2TransferAndMulticall4.662 Tgas+2.953 Tgas32.0%946 KgasPermit2 transfers followed by batched calls, commonly used for routed swaps and relayed execution.
ERC-4337 EntryPoint0x4337084d…3b5ff108handleOps1.922 Tgas+1.164 Tgas12.6%554 KgasValidates and executes batches of smart-account user operations.
Axiom trade router0x4a86009a…1fcf6f60axiomTrade0.983 Tgas+0.822 Tgas8.9%393 KgasExecutes routed token trades through a universal-router style interface.
OKX DEX router0x6e2a35a7…774c6919dagSwapTo / dagSwapByOrderId0.683 Tgas+0.433 Tgas4.7%528 KgasSplits and routes swaps across DEX paths selected by the OKX aggregator.
GMGN router0xe492912f…6cd7ce2bswap0.453 Tgas+0.317 Tgas3.4%448 KgasA second GMGN proxy used to route token swaps.
Unverified trading router0x38140f2d…9a60cd6f0x39ecce490.282 Tgas+0.282 Tgas3.1%507 KgasA newly active router-like contract. Transfers indicate token trading, but no verified ABI names the method.
ERC-4337 EntryPoint v0.70x00000000…f37da032handleOps0.395 Tgas+0.207 Tgas2.2%486 KgasValidates and executes batches of smart-account user operations.

Attribution check: “All other” combines every contract address outside the top 10. Gas is assigned to the transaction destination, so internal calls, including oracle verification, remain under that outer address. Isolating oracle gas requires call traces.

L2 gas-used scope: L2 gas used is receipt gas minus the L1 poster-gas equivalent. Nitro calls this value computeGas, but it is not a CPU-only or multigas computation measure. It feeds Robinhood Chain’s L2 backlog and excludes the L1 data fee.

What does the top-three counterfactual show?

The first chart shows which addresses accounted for recent L2 gas use. The next two compare observed outcomes with a modelled path that excludes transactions sent to the three largest destination contract addresses and replays the same Robinhood Chain pricing mechanism. The fee chart averages only the remaining transactions.

How was L2 gas use distributed?

Top 3: 47.7%. Ranks 4–10: 16.1%. Together, the top 10 account for 63.8% of all chain L2 gas used.

Average L2 gas price: observed vs counterfactual

Solid: observed onchain daily average. Dashed: the same pricing replay after excluding transactions sent to the three largest destination contract addresses.

Average transaction fee: observed vs counterfactual

Solid: observed onchain daily mean in USD. Dashed: the remaining transactions repriced by the counterfactual model.

Counterfactual comparison: on 6 September, the modelled path excluding the top three destination contract addresses has an average L2 gas price 77% lower and an average fee for the remaining transactions 84% lower. At the largest daily gap, the observed onchain price is 4.3× the counterfactual path. The comparison follows the pricing mechanism’s backlog rules; it is not a statistical causal estimate.

Why does sustained demand raise Robinhood Chain’s L2 base fee?

Nitro carries L2 gas use that exceeds its configured drain rates from one block to the next in accounting backlogs. Think of a bucket that is constantly being filled with L2 gas while gas leaks out at the configured target rate. When gas flows in faster than it leaks out, the level rises. That remaining gas adds pressure to the next base fee.

Robinhood Chain uses two constraints. Both record the same block L2 gas used, but each has its own target rate and adjustment window. J0 reacts to short spikes; J1 measures sustained load.

1 · Record L2 gas used

gL2(t)B₀B₁

gL2(t) is total receipt gas used after subtracting the L1 poster-gas equivalent. Nitro adds that same value to both backlogs; it is not divided between them.

2 · Drain each backlog

J0 · A₀ = 15 sJ1 · A₁ = 1 dayT₀ = 60 Mgas/sT₁ = 40 Mgas/s

Tⱼ sets the drain rate: the backlog grows only while demand exceeds Tⱼ. Aⱼ does not slow the drain; it scales the remaining backlog into price pressure. J0 normalizes backlog against 15 seconds of target capacity; J1 normalizes it against one day.

3 · Calculate the next base fee

Bⱼ⁻Aⱼ × Tⱼafter drain · before blockE = Σejpmin× P₄(E)

Bⱼ⁻ is the backlog after draining, before the current block’s L2 gas is added. The superscript minus marks this “pre-block” state; it does not mean the value is negative. Each remaining backlog becomes a pressure term eⱼ, and Nitro sums those terms to calculate the next base fee.

Which parameters control backlog growth and price pressure?

Robinhood Chain’s two constraints apply different target rates and time windows to the same block-level L2 gas use. The comparison below shows the active Robinhood Chain configuration and the ArbOS 61 ladder as a reference.

How do Robinhood Chain and ArbOS 61 constraints compare?

Robinhood Chain values come from decoded ArbOwner.OwnerActs events. The ArbOS 61 ladder is shown as a configuration reference only.

Minimum base fee: pmin = 0.02 Gwei. When E = 0, P4(0) = 1, so the next block is priced at 0.02 Gwei. Positive pressure multiplies this floor. Values reflect events indexed through 6 September 2026; owner-set parameters may change.

Robinhood Chain: current constraints

The active two-constraint pricing setup used in the replay below.

ConstraintTarget rate TⱼWindow AⱼStarting backlogCurrent since
J060 Mgas/s15 s0Unchanged since 10 Jul
J140 Mgas/s86,400 s9.989 Tgas3 Sep 17:08:18 UTC · block 53,578,754

ArbOS 61: comparison configuration

The six-constraint ladder is included for comparison and is not replayed in the figures. See the official Arbitrum proposal.

ConstraintTarget rate TⱼWindow Aⱼ
j010 Mgas/s86,400 s
j114 Mgas/s13,485 s
j220 Mgas/s2,105 s
j329 Mgas/s329 s
j441 Mgas/s52 s
j560 Mgas/s9 s

Robinhood Chain slow-backlog (J1) target changes

Target rate T₁Starting backlogEffective from
15 Mgas/s1.106 Tgas10 Jul 19:12:45 UTC · block 6,322,119
20 Mgas/s2.970 Tgas24 Jul 20:08:38 UTC · block 18,424,412
18 Mgas/s020 Aug 21:21:18 UTC · block 41,739,400
30 Mgas/s7.492 Tgas1 Sep 16:33:29 UTC · block 51,865,079
40 Mgas/s9.989 Tgas3 Sep 17:08:18 UTC · block 53,578,754

The 40 Mgas/s update is applied from its recorded block onward and remains active through 6 September 2026. Nitro code: L2 pricing model.

For more details: variables and replay equationsGlossary and four implementation steps

Variable definitions

t, j

t is the block step; j identifies one constraint and its backlog.

Δt

Seconds elapsed since the previous block.

Tⱼ

Target L2 gas-used rate for constraint j, in gas/s.

Aⱼ

Adjustment window for constraint j, in seconds.

Bⱼ⁻(t)

Backlog after draining, before block t is added. The superscript minus marks the pre-block state; it is not a negative value.

Bⱼ(t)

Backlog after block t is recorded.

gL2(t)

max(gasUsed − posterGas, 0) for normal transactions. Retryable execution has no poster-gas component at this step.

eⱼ(t)

Pressure from constraint j: Bⱼ⁻ ÷ (AⱼTⱼ).

E(t)

Total pressure: the sum of every eⱼ(t).

P₄(E)

Nitro’s fourth-order Taylor approximation of exp(E).

pmin

Minimum L2 base fee. Robinhood Chain uses 0.02 Gwei.

p(t+1)

L2 base fee stored for the next block.

1 · Drain the backlogs

For each elapsed second, subtract the target rate from the backlog. A backlog cannot fall below zero.

B minus j at t equals max of zero and prior backlog minus target times elapsed time
old Bⱼ− TⱼΔtnever below 0

2 · Turn backlog into pressure

Divide each backlog by its reference volume AjTj to obtain ej, then add the terms to obtain E.

Each constraint exponent equals drained backlog divided by adjustment window times target; the total exponent is their sum
e₀e₁E = e₀ + e₁

3 · Approximate exp(E)

After summing the pressure terms, Nitro evaluates ApproxExpBasisPoints(E, 4) once.

Fourth-order Taylor approximation of the exponential
E = ΣeⱼP₄(E)one Taylor-4 evaluation

4 · Set the price, then add this block

Multiply the Taylor factor by pmin, which is 0.02 Gwei on Robinhood Chain. After pricing, add the block’s L2 gas used to every backlog.

Next price equals minimum price times Taylor four, then each backlog grows by L2 gas used
E(t)P₄p(t+1)next L2 base feeafter pricinggL2(t)B₀B₁

How closely does the pricing replay match the observed price?

The replay uses Robinhood Chain’s full onchain parameter history from genesis, including the original six-constraint startup configuration. The three figures cover 10 July–6 September, matching the current J0/J1 structure introduced on 10 July. Dashed markers show every later J1 target-rate change.

What happened to Robinhood Chain’s backlogs?

J0 has a 15-second adjustment window; J1 has a one-day adjustment window. Both backlogs still drain at their own target rates, and both series begin with Robinhood Chain’s current two-constraint structure on 10 July.

J0 usually clears between bursts. J1 begins rising persistently in late August because L2 gas use remains above its target rate, carrying excess work from one block to the next.

How much pressure did each constraint contribute?

The chart plots P4(ej) for J0 and J1 from 10 July onward. Nitro sums the underlying ej terms before pricing.

Short bursts briefly lift J0. J1 drives the sustained late-August increase after demand exceeds its target rate long enough for backlog to accumulate.

How closely does the replay track the observed price?

The dark line is the observed block-header price. Green is the replay using only Robinhood Chain’s own parameter history.

The replay nearly overlaps the observed L2 base fee, which validates the equation order, parameter changes, and integer Taylor approximation used in this report.
Gas-weighted replay error over the focused 17 August–6 September window: +0.0208%. The replay calculation begins at genesis; the displayed slider range starts on 10 July. Click a legend item to hide it; double-click to show it alone. Scrolling the page does not zoom the charts.
Target rate vs adjustment window

Why did the slow backlog (J1) keep filling?

The target rate controls whether the backlog grows. When sustained L2 gas use stays above T₁, the excess is carried into J1 from block to block. When gas use falls below T₁, J1 drains.

The one-day adjustment window controls how backlog becomes price pressure. A₁ = 1 day defines the reference volume T₁ × A₁ in the denominator of e₁. It does not itself slow the drain.

How sustained L2 gas use fills the J1 backlogBlocks arrive from left to right. L2 gas use above the J1 target rate accumulates in the J1 backlog; gas use below the target lets it drain.BLOCK-BY-BLOCK L2 GAS USEJ1 target rate T₁BLOCK 01 · BELOW TARGETexcess carried forwardSLOW BACKLOG (J1)Backlog rises, then drainse₁ = B₁ ÷ (T₁ × A₁) · A₁ = 1 dayConceptual mechanism · not to scale
Watch each block arrive: gas use above the target adds excess work to J1; gas use below the target drains it. The one-day window scales the remaining backlog into fee pressure.

What does this mean for Robinhood Chain?

Transaction volume rose modestly, while L2 gas used rose much faster. The comparison weeks show 7.5% more transactions and 63.0% more L2 gas used. Much of that gas came from a small set of trading and execution contracts.

Fees kept climbing because L2 gas use stayed above the slow one-day backlog’s target rate (J1). The excess carried into later blocks and the backlog grew. The one-day adjustment window did not cause the buildup. It set the reference volume used to turn the remaining backlog into price pressure. Nitro then used that pressure to set a much higher shared base fee.

Operators need to watch two settings. The target rate controls how much sustained L2 gas use the chain can absorb before the backlog grows. The adjustment window controls how strongly that backlog affects price.

What should Robinhood Chain test next?

The replay can test parameter changes before they go live. The next step is to compare capacity, fee paths, and recovery times under different workloads.

Simulate capacity choices

Replay alternative target rates and adjustment windows against the same demand stream, then compare backlog growth, fee paths, and recovery time.

Stress different demand mixes

Model routed trading, account abstraction, oracle-heavy applications, and broad long-tail activity separately to see which workloads create sustained pressure.

Build early-warning indicators

Track L2 gas use versus target, backlog runway, and projected fee multipliers so operators can see pressure building before users experience the full price response.

Links and further reading

Official documentation, implementation references, onchain records, and related research.

Chain architectureRobinhood Chain documentationArbitrum Dedicated Blockchain, Ethereum L2, ETH gas token. Robinhood Chain Nitro nodeOfficial full-node guideRuns offchainlabs/nitro-node v3.11.2 with Robinhood Chain configuration and genesis. Onchain parametersArbOwner constraint eventsPublic transaction evidence for the current J1 target; earlier changes are linked in the table. ImplementationNitro L2 pricing modelBacklog drain, normalized exponent, fourth-order approximation, and next price. Owner interfaceGas-pricing constraints APITarget, adjustment window, and starting backlog semantics. Mechanism designMulti-constraint pricingArbitrum’s derivation of multiple backlogs and the constraint ladder. Research paperArbitrum Nitro whitepaperSection 3.3.1 derives Nitro’s backlog mechanism; the implementation studied here is multi-constraint pricing. Contract activityPons launchpad APIDocuments Robinhood Chain launchAndBuy calls used in the contract attribution. Contract sourceOKX DEX routerOpen-source router implementation for the observed dagSwap methods. Contract referenceUniswap deploymentsOfficial deployment addresses, including Robinhood Chain’s Universal Router.
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