Loeb, an activist investor who runs the hedge fund Third Point and has amassed an estimated $1.5 billion personal fortune, flew to Japan for three days of meetings with Sony and government officials, The New York Times reported Tuesday.
He also went to hand deliver a letter to Sony's Chief Executive Officer Kazuo Hirai that calls for Sony to divest itself of Sony Entertainment, which includes a major Hollywood film studio and a significant music recording business.
Loeb's hedge fund has been quietly purchasing Sony stock, so that it now owns a 6.5 percent share, making it one of the largest shareholders, the Times said.
Loeb's move, however, can also be seen as emblematic of a sudden shift in economic expectations.
After more than a decade of stagnation, there is renewed confidence in Japan's economy that has accompanied Prime Minister Shinzo Abe's agenda, which includes strong stimulus measures to prompt growth.
As a result, the yen has dropped in value to 100 to the dollar, a four-year low, which makes its exports more affordable. The Tokyo stock market's Nikkei 225 index has jumped 43 percent this year, a sharp contrast to 2011, when the index was off 5.7 percent from January to May.
Gaining some momentum is Sony itself, which posted its first annual profit in five years in 2012.
"Under Prime Minister Abe's leadership, Japan can regain its position as one of the world's pre-eminent economic powerhouses and manufacturing engines," Loeb wrote in his letter.
Sony, so far, has insisted that none of its divisions are up for sale.
"We are focused on creating shareholder value by executing on our plan to revitalize and grow the electronics business, while further strengthening the stable business foundations of the entertainment and financial services businesses," said company spokesman Shiro Kambe in a statement.
"We look forward to continuing constructive dialogue with our shareholders as we pursue our strategy," the spokesman said.