July 12 (Reuters) - Billionaire investor Mario Gabelli's

investment firm is seeking more details about the valuation of

National Amusements assets, the investor told Reuters on Friday,

signaling the firm may challenge a landmark entertainment

industry deal inked this week.

Skydance Media and Paramount Global ( PARAA ) agreed on

Sunday to merge, in a deal that would entail Skydance acquiring

the Redstone family's holding company, National Amusements,

which owns a controlling stake in Paramount.

Gabelli Funds, which owns nearly 4.9 million Class-A voting

shares in Paramount, is seeking greater transparency around the

National Amusements deal, according to another source at

Gabelli. It sent a letter to Paramount's general counsel on

Friday, requesting information, the source said.

"Operation fish bowl ... most likely starts today," Gabelli,

the 82-year old chief executive of Gabelli Asset Management

Company Investors wrote on social media platform X.

Skydance Media and its deal partners plan to acquire

National Amusements for $2.4 billion in cash. In a related

transaction, the independent media company led by David Ellison

would merge with Paramount in an all-stock deal that values

Skydance at $4.75 billion, creating a company with an enterprise

value of $28 billion.

The companies have declined to disclose how much money Shari

Redstone would be paid for her Paramount shares compared to

other shareholders.

Skydance's deal to buy Redstone's National Amusements values

the holding company at $37.79 per Paramount share, and the

Redstone family stands to pocket $27.55 per Paramount share

because of $650 million in net debt.

This does not strip out some of the other assets that

National Amusements holds besides its Paramount stake, including

movie theaters and real estate. National operates 759 screens in

the U.S., UK and Latin America.

The parties have declined to provide sufficient information

for a direct comparison with the $23 that Class-A stockholders

will receive for each share and the $15 Class-B stockholders

will receive for each share.

National Amusements and Paramount did not immediately

respond to requests for comment.

Gabelli has privately said for months that the deal could be

harmful to investors and now appears to be laying the groundwork

to possibly challenge it in court.

Earlier this year, the Employees Retirement System of Rhode

Island, an investor in Paramount Global ( PARAA ), asked for documents

related to talks between the company and Skydance.

Rhode Island argued that it wanted to be sure that the best

price is negotiated for Paramount.