JPMorgan analysts have warned clients that cryptocurrency markets are looking frothy after the August trading boom saw spot market trading volumes once again top $1 trillion. 

In a note to clients reported by Markets Insider, the JPMorgan analysts suggested valuations in crypto markets, especially altcoins and nonfungible tokens (NFT), are getting too high.

“The share of altcoins looks rather elevated by historical standards and in our opinion it is more likely to be a reflection of froth and retail investor ‘mania’ rather than a reflection of a structural uptrend.”

The bank’s analysts noted that altcoin trading now accounts for about 33% of the total cryptocurrency market, up from just 22% at the beginning of August.

Although many crypto traders are delighted at the price increases, the analysts believe the apparent uptick in interest may not be substantial enough to be maintained for an extended period of time.

The analysts also highlighted the net inflow of retail investments to United States stocks, which stood at $13 billion through August with help from Reddit-inspired day traders, following a record high of $16 billion in July. They believe the buying frenzy spilled over into NFTs, decentralized finance (DeFi) and smart contract platforms, including Solana, Binance Smart Chain and Cardano.

Spot investors have pushed several major altcoins well above their previous all-time highs. Cardano (ADA) traded above $3 for the first time on Thursday, and Solana (SOL) is up over 400% since the beginning of August, according to CoinMarketCap.

Bitcoin (BTC) has also shown tremendous strength by rallying back above $50,000 for the first time since May 2021.

Related: Surge in activity and token prices show ‘DeFi Summer 2.0’ already started

Meanwhile, OpenSea, one of the largest NFT marketplaces, has seen trading volume on its platform increase by over 76,000% since the beginning of 2021. Trading volume had surpassed $4 billion by Tuesday, Aug. 31, according to DappRadar.

Figures for OpenSea in August. Source: DappRadar

Figures from Dune Analytics show that the trading volume of DeFi coins increased 152% month-on-month in August, bringing total trading volume past $11 billion. Several trading platforms and DeFi protocols have reached milestones, with Uniswap surpassing Coinbase’s daily trading volume on Monday and Synthetix regaining $1 billion in total value locked.