Fantex, a brokerage firm based in San Francisco, will soon begin a campaign to sell shares of Buffalo Bills quarterback EJ Manuel on the stock market.

Manuel signed a "brand contract" with the company in February, becoming one of the first athletes to receive an up-front payment from the firm in exchange for a stake of his future income.

Investors can begin reserving shares of Fantex's Manuel stock on May 5. Once the initial public offering is closed and declared effective by the Securities and Exchange Commission, the shares will be available for trading on the secondary market under the ticker symbol EJMLL.

Fans will be able to buy a piece of EJ Manuel, in the form of $10 shares being offered by Fantex Brokerage Services. Sam Greenwood/Getty Images

In total, Fantex will offer 523,700 shares of Manuel stock at $10 per share.

The company will pay $4.97 million to Manuel for a 10 percent interest in his "brand income," which includes his contract, endorsements, and any post-career income such as a broadcasting deal.

"EJ is a young player [who] is evolving -- a good-looking, smart, articulate individual that has interests beyond just football," Fantex CEO Buck French told ESPN. "So our goal is to work with him to create an audience via social media that's actually interested in his other interests beyond football."

Fantex's prospectus for Manuel's stock estimates that the quarterback will earn $104 million during and after his career. Using statistical analysis of other NFL quarterbacks who played from 1980 through 2012, that amount is then discounted at 14.6 percent to account for the risk that Manuel will not earn his future expected income.

"If you think about what a 'CCC' rated bond yields -- that would be considered a junk bond -- again, this is just a comparable of risk analysis, that bond today yields about 8.5 percent," French said. "So we felt comfortable, given the volatility of cash flow streams in the NFL, that a weighted average discount rate across that of 14.6 percent -- to include his post-career side -- was a reasonable estimation to adjust those cash flows for risk."

San Francisco 49ers tight end Vernon Davis became the first publicly traded athlete Monday when Fantex held an limited initial public offering of Davis' stock. First offered at $10 per share, his stock was trading at $11 by Wednesday.

Manuel, 24, signed his four-year, $8.9 million rookie contract last year. The 16th overall pick in the 2013 draft enters this season as the Bills' starting quarterback but went 4-6 as the starter last season in between three separate knee injuries.

Fantex postponed an offering of Houston Texans running back Arian Foster last year after Foster suffered a season-ending injury, but the company doesn't share the same concerns about Manuel's injuries.

"It's hard to find a football player that hasn't had some type of knee or leg injury," French said. "We evaluated his medical records and we were comfortable moving forward with him, given the risk."

Technically, fans don't buy shares of the athletes. They're buying shares of Fantex, so as the company collects more money, the stock should rise. The stock trades on Fantex's website's platform, as opposed to standard exchanges like the NYSE and NASDAQ.

"From an investor standpoint we absolutely see this as an opportunity," French said. "This is a registered, real security with the SEC. It's not fantasy, it's not some gimmick."

Information from ESPN.com's Darren Rovell and The Associated Press was used in this report.