Jan 12 (Reuters) - Crypto asset manager Bitwise said on Friday that $240 million flowed into its spot bitcoin exchange-traded fund (ETF), the most of the 10 such products that began trading on Thursday.

The U.S. Securities and Exchange Commission approved 11 spot bitcoin ETFs this week, including BlackRock's iShares Bitcoin Trust, Grayscale Bitcoin Trust, and ARK 21Shares Bitcoin ETF, among others, after a decade-long tussle with the digital asset industry. On the first day of trading, $4.6 billion worth of shares changed hands across all the products, according to LSEG data from Thursday which tracks total trading activity, including inflows and outflows. Reuters could not immediately verify Bitwise's data.

Grayscale, BlackRock and Fidelity dominated total trading on Thursday, the LSEG data showed.

The products mark a watershed moment for the cryptocurrency industry that is set to test whether digital assets - still viewed by many professionals as risky - can gain broader acceptance as an investment. The market is closely watching inflows during their first few days of trading.

"We think that this will become a market measured in the tens of billions of dollars," said Matt Hougan, chief investment officer at Bitwise.

The ProShares Bitcoin Strategy ETF, the first bitcoin futures ETF approved by the SEC in 2021, accumulated $1 billion in assets within its first days of trading.

"Matching BITO's first-week performance would indeed signify a significant success, especially given the current state of the market cycle," said Anthony Rousseau, head of brokerage solutions at TradeStation.

Grayscale was approved to convert its existing bitcoin trust into an ETF on Thursday, overnight creating the world's largest bitcoin ETF, with more than $28.6 billion in assets under management. Its product had outflows of $95 million on Thursday, according to a source familiar with the matter.

The SEC had previously rejected all spot bitcoin ETFs on investor protection concerns. SEC Chair Gary Gensler said in a statement on Wednesday that the approvals were not an endorsement of bitcoin, calling it a "speculative, volatile asset."

Still, the regulatory nod sparked intense competition for market share among the issuers.

Franklin Templeton on Friday slashed the fee for its bitcoin ETF to 0.19% - the lowest yet - and waived fees entirely on the product's first $10 billion in assets under management until August.

After its ETF started trading on Thursday, Valkyrie cut its fees a second time to 0.25%. Its Valkyrie Bitcoin ETF saw $29.44 million flow in during its first day of trading, the company said. Reuters could not immediately verify that number.

Valkyrie CEO Leah Wald, speaking to Reuters after the market close on Thursday, called it "a good successful trading day."

The price of bitcoin, the world's largest cryptocurrency, was last down 5.32% at $43,696. (Reporting by Hannah Lang in Washington and Suzanne McGee Editing by Michelle Price, Kirsten Donovan and Matthew Lewis)