These are an example of derivative securities; the payout of the "shares" is derived directly from the earnings of the player, which is a very risk stream of future cash flows. Bonds pay a coupon rate that is specified, but risky; these have a payment that is both risky and unspecified, but tied to a particular variable (player earnings). Derivatives are demonized in the press, but there are lots of things that are well-accepted derivatives, like stock options. As mentioned above, we don't know the formula for how much of the earnings are actually paid out to investors, so we can't do much modeling on the possible valuation. Perhaps the best analogy for this are the so-called "Bowie bonds". David Bowie sold bonds which paid out over time based on the sales of his previous albums rather than at a specific coupon rate. Another somewhat similar instrument would be bonds that have an interest rate that fluctuates with oil prices. Investors have been very interested in these assets, and baseball player contracts would also be at least potentially interesting to certain investor profiles. I'm not sure I buy the idea that it makes a player less likely to sign an early extension, but it's possible. Dozier's contract that bought out his late arb years was 4 years, $20 million. Would a $3-4 million up-front payment in exchange for 10% of all future earnings have persuaded him to skip the deal and hit free agency earlier? As others have also mentioned above, there's still a ton of risk in playing MLB. If you sign the deal early, 10% of what you lose with potential arb raises is money you don't get anyway. It will also be interesting to see which players want to do this. Players who are marginal probably have the most interest in doing it, but they would also see the least investor interest. At least they would see the lowest prices from investors. Maybe the best marketing strategy would be to try and sell these shares to people who pay hundreds of dollars a year to be in fantasy baseball leagues. In my opinion, this isn't gambling any more than any type of equity-based investing. It's just a different kind of asset, with much less complex possible cash flows but much higher specific, uninsurable risk. You could diversify by getting shares in more players, but that only diversifies some of the risk. Declining interest in baseball or anything else that slows growth in the salary pools would hit at least most players.