Shares of companies with substantial cryptocurrency holdings soared to double-digit gains in Tuesday trading as renewed optimism for the introduction of spot bitcoin ETFs kindled a short squeeze in derivatives based on the oldest digital asset.

Bitcoin BTC itself rose to $33,800 in New York afternoon trading, according to CoinGecko. It ended Friday at $29,493 and crossed the $30,000 threshold late on Sunday. At its current level, bitcoin has doubled for this year and accounts for 51% of the cryptocurrency market’s $1.3 trillion value, the most since 2021.

Bitcoin Busts Through ,000

The prospect of U.S. exchange-traded funds based on actual bitcoin holdings instead of futures contracts has become the focus of cryptocurrency trading and also equities closely associated with digital assets. The idea is that the widespread ability to own bitcoin through easy-to-trade ETFs will substantially boost demand for the token and by extension cryptocurrencies in general.

Microstrategy, essentially a closed-end bitcoin fund attached to a business-software company, gained 13% to $424.87, bringing, triple the level at the end of last year. The company revealed in a government filing last month that it owned $4.68 billion of bitcoin acquired at an average price of $29,582, which means that co-founder Michael Saylor’s strategy to stockpile the crypto has turned positive with the latest rise.

Bitcoin miner Marathon Digital rose 12%, while rival CleanSpark was up 11% and the diversified crypto-services company Galaxy Holdings gained 14%.

Existing ETFs notched lesser gains, with VanEck Bitcoin Strategy ETF and ProShares Bitcoin Strategy each rising 7%.

The U.S. Securities and Exchange Commission has adamantly refused to allow ETFs based on the price of bitcoin (BTC), which it has said is subject to manipulation, even though it allows funds that invest in futures contracts on the token. That practice that led to a black eye for the agency when a federal appeals court ruled the policy was “arbitrary and capricious.”

Earlier this month, the SEC let pass a deadline to appeal the court’s order that it consider Grayscale’s application to change its existing bitcoin trust to an ETF, and the agency has begun to negotiate with several companies that are seeking to start such funds from scratch.

“After the SEC declined to appeal its loss to Grayscale in the circuit court, an approval of a physically backed BTC ETF in the U.S. became increasingly more likely,” James Butterfill, head of research at European crypto asset manager CoinShares, tells Forbes by email. He adds that BlackRock BLK , the world’s largest asset manager, had applied for a CUSIP identifier for its planned offering, a necessary step for listing a security.

Market participants are positioning for bitcoin ETFs to be approved early next year, Butterfill says.

Tuesday’s acceleration of bitcoin gains was abetted by a short squeeze, says Bradley Duke, chief strategy officer at ETC ETC Group, a provider of exchange-traded products based on cryptocurrencies. “The rally wiped out some large leveraged short positions, causing a short squeeze with en masse buying from short sellers closing out their bearish positions, which in turn boosted the Bitcoin price even more,” he tells Forbes by email.

Luuk Strijers, chief commercial officer at crypto derivatives exchange Derbit, says bitcoin is leading the derivatives activity, rather than the other way around, with the prospect for ETFs, the main driver. Still, volume on Derbit is running at levels not seen since 2021.

This week’s action follows a brief bitcoin rise above $30,000 in September after it was falsely reported that the SEC had approved a bitcoin ETF. Once it became clear that the story was inaccurate, the token subsided to about $28,000, indicating that approval had not been priced into the market at that point. Despite the rising prices, bitcoin remains 51% below its November 2021 high of $69,044 and the market value of all cryptos is barely a third of its record that year of $3 trillion.

“In the past 48 hours we have seen a surge in crypto prices, but as the adage goes, ‘one swallow does not a summer make,’ and I think the same holds true for crypto,” ETC’s Duke writes. “It’s really impossible to know if a few days of upward price movements is just a flash in the pan or the beginning of a long bull run.”