Solana is a proof-of-stake Layer 1 blockchain. Its native token is SOL. It handles payments, stablecoins, DeFi and tokenised assets on one base layer rather than through rollups. The biggest recent change came on 21 October 2026, when Solana activated Alpenglow on mainnet. Alpenglow replaces the TowerBFT voting layer and targets finality of roughly 150 milliseconds, down from about 12.8 seconds. As of 25 October 2026, DefiLlama shows about $5.76 billion in DeFi value locked on Solana and about $15.5 billion in dollar stablecoins. The weak points are a history of outages, a shrinking validator set, and client diversity that is still limited.
What changed in October 2026: Alpenglow goes live
According to Solana's official Alpenglow page, the upgrade shipped in Agave 4.3. It became active at the start of epoch 1064, which began on Wednesday, 21 October 2026, at about 13:36 UTC. Validators had to run v4.3.2 of Agave, Jito-Solana or Harmonic Salsa. Firedancer and Frankendancer were not supported for the migration.
What is live and what is not:
- Votor (phase 1) is live. It replaced TowerBFT's voting layer completely. The page calls the 150 ms finality target "an expectation, not a constant".
- Rotor (phase 2) is not scheduled. It is meant to replace Turbine, the block-propagation layer, in a later release.
- Proof of History no longer paces block production. Tick entries have been removed from the shred stream.
- Execution is unchanged. The SVM, transaction format and fees stay the same.
- Developer note. The
confirmedcommitment level is due to be removed in a later release, so the page tells new code to targetfinalized.
Several other mainnet changes came before Alpenglow in 2026:
- Bigger blocks. SIMD-0286 raised the block limit to 100 million compute units. The Solana changelog of 30 July 2026 reported it as activated.
- Shorter slots. The Solana Foundation's August 2026 roundup says the target slot time fell from 400 ms to 350 ms, then to 300 ms on 28 August.
- Record usage. The same roundup reports a record 216 million non-vote transactions in one day in August 2026. It also reports 1.32 billion non-vote transactions in the week of 17 to 23 August.
How Solana works now
Accounts and parallel execution
Solana stores all state in accounts. Each account sits at a 32-byte address and holds lamports (the smallest SOL unit), data, an owner program, an executable flag and a rent epoch. Only the owning program can change an account's data or debit its lamports.
Transactions declare in advance which accounts they will read and which they will write. This is what makes parallel execution possible. Anza's runtime documentation states the rule: transactions that touch only read-only accounts run in parallel, and transactions that write to the same account run one after another. Solana calls this parallel runtime Sealevel.
Two limits from the official documentation matter to builders:
- Transaction size: at most 1,232 bytes. That is the IPv6 minimum MTU of 1,280 bytes minus 48 bytes for headers.
- Accounts per transaction: at most 64 accounts, or 96 for v1 transactions under SIMD-0596.
Consensus and block propagation
- Proof of stake. Validators vote with stake, and SOL holders can delegate SOL to them.
- Votor. Since epoch 1064, Alpenglow's Votor handles voting and finality instead of TowerBFT.
- Turbine. Blocks are still spread across the network in "shreds" through Turbine until Rotor replaces it.
- Proof of History. Older guides present PoH as the clock that drives Solana. Since Alpenglow, PoH no longer paces block production.
Fees
Fees are set in lamports, not dollars, so the dollar cost moves with the SOL price. Solana's fee documentation sets out the rules:
| Fee part | Amount | Where it goes |
|---|---|---|
| Base fee | 5,000 lamports per signature | 50% burned, 50% to the validator |
| Priority fee | Optional, set by the sender | 100% to the validator |
SOL supply
SOL has no fixed maximum supply. New SOL is issued as staking rewards. The schedule in Solana's documentation starts inflation at 8% a year, cuts it by 15% each year, and ends at a long-term rate of 1.5%.
In 2026, governance proposal SGP-0002 ("Double Disinflation") passed with 67% support, according to the Foundation's August 2026 roundup. It doubles the annual cut from 15% to 30%. The roundup projects about 18.9 million fewer SOL issued over six years. The July 2026 changelog lists the proposal as merged.
Solana's 2026 core upgrades, step by step
Step through the 2026 mainnet changes, from bigger blocks to Alpenglow, and see what is live and what has no date yet.
- 30 July 2026Bigger blocks (SIMD-0286)done
The Solana changelog reported SIMD-0286 as activated, raising the block limit to 100 million compute units.
- 28 August 2026Target slot time cut to 300 msdone
The Solana Foundation's August 2026 roundup says the target slot time fell from 400 ms to 350 ms, then to 300 ms on 28 August.
- 21 October 2026Alpenglow Votor goes live at epoch 1064done
Shipped in Agave 4.3 and active from about 13:36 UTC. Votor replaced TowerBFT's voting layer and targets finality of roughly 150 milliseconds, which the official page calls an expectation, not a constant. Firedancer and Frankendancer were not supported for the migration.
- Not scheduledRotor (phase 2) replaces Turbinepending
Rotor is meant to replace Turbine, the block-propagation layer, in a later release. Until then, blocks still travel in shreds through Turbine.
- Later release'confirmed' commitment level removedpending
The confirmed commitment level is due to be removed in a later release, so the official page tells new code to target finalized.
This lists the dated protocol steps the article covers. It does not show measured finality after Alpenglow, Firedancer's stake share or when the doubled disinflation rate activates, and it is not investment advice.
The ecosystem: where activity sits
Stablecoins and payments
Payments are where the network is used most clearly outside crypto trading:
- USDC settlement by Visa. In September 2023, Visa said it was extending USDC settlement to Solana in pilots with merchant acquirers Worldpay and Nuvei. In December 2025, The Block reported that Visa launched USDC settlement on Solana for U.S. financial institutions, with Cross River Bank and Lead Bank among the first participants.
- PYUSD. The dollar stablecoin issued by Paxos became available on Solana on 29 May 2024. It was its first network outside Ethereum.
- USDPT. Western Union launched this stablecoin on Solana in May 2026. Anchorage Digital Bank N.A. issues it, and it is used for settlement between Western Union and its agents. The first markets were the Philippines and Bolivia, according to The Block and Anchorage's announcement. In August 2026, the Foundation reported a USDPT-backed Visa card ("Stablecard") in 37 markets.
- Total supply. As of 25 October 2026, DefiLlama shows about $15.5 billion in dollar-pegged stablecoins on Solana.
Token Extensions
Institutional tokens on Solana usually rely on the Token Extensions program (Token-2022). Its options include:
- transfer fees
- confidential transfers
- interest-bearing balances
- transfer hooks
- non-transferable tokens
- a permanent delegate
- pausing
- default account states
- on-chain metadata
Some extensions cannot be used together. Most cannot be added after an account is set up, so issuers have to choose them at the start.
DeFi, tokenised funds and ETFs
- DeFi. DeFi value locked on Solana was about $5.76 billion on 25 October 2026, per DefiLlama. The main activity is lending, liquidity pools on decentralised exchanges, and liquid staking.
- Tokenised funds. The Foundation's August 2026 roundup lists a tokenised high-income fund from Securitize and Neuberger Berman. It also lists a memorandum with Shinhan Asset Management to test a Korean-won tokenised fund.
- ETFs. The same roundup counts nine U.S. Solana ETFs with about $1.34 billion in cumulative net inflows by the end of August 2026. It says Bitwise's BSOL became the first U.S.-listed Solana ETF to pass $1 billion in assets.
Memecoins
The Foundation reported $5.2 billion in weekly memecoin spot volume on Solana, the highest weekly figure of 2026. Memecoin trading brings many users and fees, and it can also produce sudden traffic spikes.
Risks and limits
Outage history
Solana has stopped finalising blocks more than once. The official post-mortems for the two most recent major incidents:
- 25 February 2023, about 19 hours 42 minutes. A faulty validator produced an oversized block. Shred-forwarding services then re-sent duplicate shreds in loops, overloading deduplication filters. Validators were in vote-only mode, and no finalised transactions of economic value were rolled back.
- 6 February 2024, about five hours (09:53 to 14:55 UTC). A bug in the cache for programs on a legacy loader caused an infinite recompile loop. Validators on v1.17, over 95% of stake, stalled, and consensus stopped.
Earlier halts happened in 2021 and 2022.
Fewer validators
Cointelegraph, citing Solana Compass data, reported on 29 January 2026 that the validator count fell 68%, from a peak of 2,560 in March 2023 to 795. Over the same period the Nakamoto coefficient fell from 31 to 20. That coefficient is the smallest number of validators whose combined stake could halt the network.
Independent operators say running a validator has become hard to make pay. Fewer validators means fewer parties would need to fail or collude to stop the chain.
Client diversity
In February 2024, one bug stopped validators holding over 95% of stake. That shows how much risk sits in a single dominant codebase.
Jump Crypto is building Firedancer, a separate validator client written in C. Decrypt reported in September 2024 that Frankendancer, a hybrid of Firedancer and Agave code, was running on mainnet.
Firedancer was also not supported for the Alpenglow migration. Client diversity therefore did not improve during the October upgrade.
Smart-contract and economic risk
Fast settlement does not protect protocols from bad design. Audits, time in production, and how a protocol's oracles and collateral rules work matter more than the chain it runs on.
New-upgrade risk
Alpenglow changes the core of consensus. It has been live for only a few days, so there is no long record yet of how it behaves under mainnet load.
What to watch next
- Alpenglow data. Measured finality and stability after epoch 1064, and a date for Rotor.
- Firedancer support. Whether Firedancer supports Alpenglow, and how much stake moves to it.
- Disinflation. When the doubled disinflation rate activates on mainnet.
- Validators. Whether the validator count and Nakamoto coefficient stabilise.
- Payments. Payment volume from Visa settlement and USDPT, which shows real use more directly than DeFi value locked.
The ETF, memecoin, slot-time and usage figures above come from the Solana Foundation's own reports; the DeFi and stablecoin totals are DefiLlama snapshots from 25 October 2026.
