(Reuters) - Asset managers, ranging from wealth management companies to hedge funds and pension funds, boosted allocations to U.S. exchange-traded funds tied to the price of bitcoin in the fourth quarter of 2024, as the price of the world's largest cryptocurrency soared 47%, according to recent regulatory filings.

The State of Wisconsin Investment Board disclosed in its quarterly 13-F filings with the Securities and Exchange Commission that its bitcoin ETF holdings more than doubled in the final three months of last year, to 6 million shares of the iShares Bitcoin Trust ETF ( IBIT ) by December 31. The fund, which was the first fund of its kind to report investing in crypto following the debut of bitcoin ETFs, couldn't immediately be reached for comment.

Other large investment funds also boosted their holdings in the ETFs, which launched in January 2024.

Tudor Investment Corp, a systematic hedge fund manager, reported its holdings of the iShares ETF -- now the largest of the pack, with more than $55 billion in assets -- climbed to 8 million shares, from 4.4 million shares. The value of those holdings also soared, reflecting bitcoin's jump in value, hitting $426.9 million, up from $159.9 million at the end of September. Tudor didn't immediately respond to a request for comment.

An Abu Dhabi sovereign wealth fund, Mubadala Investment Co, reported its first foray into bitcoin ETFs in the fourth quarter, taking a 8.2 million share stake in the iShares ETF that was worth $436.9 million.

Hedge fund Hunting Hill Capital had no exposure to these ETFs as of the end of the third quarter, but by December 31 had re-emerged as a significant investor, with positions valued at about $131 million by the end of the year.

"We've been actively trading within the broader crypto ETF complex, and the timing of the third-quarter filing may not have aligned with when we bought and sold various ETFs," said Adam Guren, founder and chief investment officer of the firm.

The ranks of those adding to positions included financial advisory firms whose clients have been eager buyers of bitcoin ETFs. Cetera Advisors and NewEdge Advisers were among firms that boosted holdings in several of the ETFs, including products offered by Fidelity, ARK Investments and Invesco ( IVZ ).

Other investors were more selective, the filings showed. Cresset Asset Management boosted its exposure to ETFs carrying lower fees, said Jack Ablin, the firm's chief investment officer.

"It's also possible right now to get attractive options pricing for collar strategies, allowing us to protect the downside while giving away less of the upside in exchange, on these bitcoin funds," Ablin said.

The 13F filings are one of the few ways to get insight into how institutional investors are positioned at the end of every quarter. The positions may not reflect current holdings.