Derivatives data shows that Ether (ETH) traders are feeling less bullish when compared to Bitcoin (BTC). Even though the altcoin captured a nearly 200% gain in the first half of 2021 versus Bitcoin’s modest 22% price increase, traders seem to be more affected by Ether’s recent underperformance.

Institutional flow also backs the decreased optimism seen in Ether derivatives, as ETH investment vehicles suffered record outflows this past week while Bitcoin flows began to stabilize. According to data from CoinShares, Ether funds experienced a record outflow of $50 million this past week.

Take notice of how Ether is underperforming Bitcoin by 16% in June. The London hard fork is scheduled for July, and its core proposal — dubbed as EIP-1559 — will cap Ethereum’s gas fees. Therefore, the price action could be related to unsatisfied miners as the network migrates out of Proof-of-Work (PoW).

For this reason, Ether investors have reason to fear because uncertainties abound. Perhaps miners supporting a competing smart-contract chain or some other unexpected turn of events could further negatively impact Ether price.

Whatever the rationale for the current price action, derivatives indicators are now signaling less confidence when compared to Bitcoin.

Ether’s December futures premium shows weakness

In healthy markets, the quarterly futures should trade at a premium to regular spot exchanges. In addition to the exchange risk, the seller is ‘locking up’ funds by deferring settlement. A 4% to 8% premium in the December contracts should be enough to compensate for those effects.

A similar effect occurs in almost every derivatives market, although cryptocurrencies tend to present higher risks and have higher premiums. However, when futures are trading below this range, it signals that there is short-term bearish sentiment.

The above chart shows the Bitcoin December futures premium recovering to 3.5% while Ethereum contracts failed to follow. While both assets displayed a neutral-to-bearish indicator, there’s evidence that the altcoin investors are less optimistic about a short-term recovery.

Related: Key Bitcoin price indicator flashes its ‘fifth buy signal in BTC history.’

Another leg down will do even more harm to altcoins

Another thesis that could negatively impact Ether’s premium is the impact of a potential negative 30% performance from Bitcoin. Filbfilb, an independent market analyst and the co-founder of the Decentrader trading suite, said that a 30% crash in the Bitcoin could prompt altcoins to drop twice as hard.

Clem Chambers, the chief executive of the financial analytics website ADVFN, also predicted another potential leg down, which would repeat the late-2018 crypto winter period. Chambers claims Bitcoin could capitulate and fall back towards $20,000.

While the overall market sentiment is neutral-to-bearish, it seems sensible to predict a more daunting scenario for Ether, including uncertainties from the transition to Proof-of-Stake (POS).

The views and opinions expressed here are solely those of the author and do not necessarily reflect the views of Cointelegraph. Every investment and trading move involves risk. You should conduct your own research when making a decision.