Yahoo Japan Corp. proposed a "merger of equals" with Yahoo Inc. — but was rebuffed — during a process lasting several months that eventually led to Verizon Communications Inc. acquiring the U.S. internet company's core assets for more than $4.8 billion, according to a regulatory filing detailing the sales effort.

The board of Yahoo Japan in February sent a letter to Yahoo Chairman Maynard Webb and Chief Executive Officer Marissa Mayer about a deal that would hand the company's shareholders 50 percent of the combined entity — and about $14 billion in cash, according to the filing made Friday. It also contemplated a commitment from Alibaba Group Holding Ltd. to purchase about half of Yahoo's stake in the Chinese e-commerce company. The deal was rejected because it offered no premium and would have triggered a full tax hit for the shares of Alibaba.

"After careful consideration, the Strategic Review Committee concluded that the terms described in Yahoo Japan's letter were not compelling," the company said in the filing.