Solana Recap (August 31 to September 20, 2026): Three Upgrades, a Waiting Mandate, Two US Signals

This recap covers three weeks, from August 31 to September 20, and replaces the individual weekly editions for that period. The dominant theme was the protocol: three of the announced upgrades reached mainnet, one of them later than planned. Alongside that: the status of the disinflation doubling, and two decisions by US regulators on September 17, both directly relevant to Solana products.

Protocol: Three Upgrades in Three Weeks

Rent drops in two stages: The first rent stage went live on mainnet on September 3 (6,333 lamports per byte), the second on September 11 (5,080). Together that is roughly 27 percent below the original value. The remaining three stages toward the 90 percent cut are expected only with Agave 4.4 in November. → Agave article with update
Transactions up to 4,096 bytes: The new v1 transaction format has been live on mainnet since September 15, six days after the targeted September 9. The previous 1,232-byte limit no longer applies to v1 transactions; older formats keep working. → Agave article with update
250ms slots: Since September 18, mainnet targets four slots per second, per the official changelog; an epoch now lasts roughly 30 instead of 36 hours. The final 200ms stage has no mainnet date yet. → Slot time thread

Tokenomics: The Mandate Waits for Code

SIMD-0550 not yet active: The disinflation doubling approved in August had not taken effect as of mid-September. Per Anza, SIMD-0607 must ship first: staking reward calculation moves to integer arithmetic so that Agave and Firedancer compute exactly the same result. That is to come with Agave 4.4. Until then, the emission curve runs unchanged. → Tokenomics thread

Regulation: Two US Signals on September 17

SEC “Innovation Exemption” for tokenized stocks: The US securities regulator issued a five-year exemption under which so-called Tokenized Securities Venues may trade tokenized US stocks (NMS stock) without registering as an exchange. Conditions per the SEC: permissioned AMM pools, the same rights as the traditional stock, publicly auditable smart contracts on public blockchains, and a trading halt whenever the primary exchange pauses. The SEC names no specific chain. The rule applies to the US market, not the EU. → SEC release
CFTC extends Phantom’s relief: With Staff Letter 26-25, the CFTC’s Market Participants Division extended the relief Phantom received for its wallet in March to all providers of “passive software.” Such apps and wallets may connect users to registered derivatives venues without registering as an introducing broker. The conditions: no custody, no buy or sell signals, and no discretion over order routing. → CFTC release

Outlook: Alpenglow

The next major stage: After this recap’s window, Anza cleared Agave 4.3 for mainnet, and the Alpenglow migration began on the public testnet. There is no mainnet date; per Anza, the often-cited September 28 is not an Alpenglow date. → Alpenglow on testnet

Deeper Reading

Alpenglow: Solana’s New Consensus Explained — the next major stage
Tokenized Stocks on Solana Explained — background to the SEC exemption
Solana Fees Explained — what larger transactions and rent mean for costs

Dates for future protocol stages are developer planning figures and may shift; regulatory information refers to the US.

Sources

Primary sources are listed in each linked individual report.
Solana — Changelog, 18 September 2026
Previous week: Solana Weekly Recap (30 August 2026)