"Exposing one lie is the same as exposing 1,000 lies," Ramey told CNBC via email. "He (Ackman) can't discern the difference anymore between truth and his fictional view of events."
Ramey provided CNBC with a series of emails he claims prove that he voluntarily left his job at Davidson. In one correspondence, dated January 21, 2014, Ramey emailed John Rogers, a Senior Vice President in charge of Institutional Research, alerting him of his plans to leave the firm in early February. In a return email, sent the following day back to Ramey and also obtained by CNBC, Rogers responds, "I am sorry to see you leave Davidson, but understand the opportunity you have."
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Ramey also provided an email he sent directly to Ackman on Tuesday, following the hedge fund manager's presentation, demanding a retraction—urging Ackman to "correct it or deal with it."
When reached for comment by phone, Ackman responded to CNBC by email, saying "I received an email from Tim Ramey complaining about a statement I made in the presentation that suggested that he may have been fired by D. A. Davidson. Tim has told me that he was not fired. Please make sure to correct the record."
On Tuesday afternoon D.A. Davidson & Co. confirmed the conditions of Ramey's departure from the firm.
"There is no truth to the suggestion that Tim Ramey was fired from D.A. Davidson & Co. He left on his own accord. We wish him well," the company said, in a statement.
—By CNBC's Scott Wapner