(Read more: 5 industrials Cramer says to become 'anointed')
According to attendees, Lautenbach said the company could increase its margins in the next few years by reducing selling, general and administrative expenses and growing business with current clients like Facebook and eBay, who use their software for online client purchases. The presentation was titled "Unlocking Value: The Transformation of Pitney Bowes."
Lautenbach was named CEO on Dec. 3, when the stock was trading around $11.60. Shares are up nearly 78% for the year, including a gain of more than 4 percent on Tuesday to $18.93.
The company announced late Tuesday that it had successfully completed the previously announced sale of Pitney Bowes Management Services for $400 million in cash to private equity firm Apollo Global Management. Proceeds from the sale of the business will be used to pay down debt, according to a press release.
(Read more: Pitney Bowes completes deal with Apollo)
"Short sellers have dramatically covered positions as the share price trades close to annual highs. The percentage of shares on loan has reduced from over 25 percent at the end of July to 15.5 percent today," said Alex Brog of Markit, which tracks daily short interest in stocks.
Brog notes that there are still plenty of people betting against the company.
"Demand to borrow the stock remains high when compared to the average across the S&P 500 of just over 2 percent," Brog said in an email to CNBC.com.
(Read more: Short sellers raising bets on S&P 500 stocks)
Stanton Green, OTR's president and CEO, confirmed the dinner occurred but declined to comment on the contents or attendees. He added only that the firm's events are geared towards current and prospective long investors, not shorts.
Recent OTR events have featured former CIA director General Michael Hayden and former Federal Reserve chairman Paul Volcker, according to people familiar with the firm.
Carol Wallace, director of external communications at Pitney Bowes, did not immediately respond to a request for comment.
The largest owners of Pitney Bowes stock, according to June 30 regulatory filings, are State Street (31,259,055 shares); Vanguard Group (12,976,028 shares); and BlackRock Fund Advisors (11,647,485 shares). Large hedge funds include Bain's Absolute Return Capital (3,950,071 shares); Saba Capital Management (a call of 3,036,500 shares); and JAT (2,626,173 shares).
—By CNBC's Lawrence Delevingne. Follow him on Twitter @ldelevingne.