But by the time Snapchat parent company Snap actually goes public, expected as soon as March, there’s no guarantee “SNAP” will be available (even though the ticker doesn’t currently trade on any U.S. stock exchange). Unlike other corporate matters, which Snap co-founders Evan Spiegel and Bobby Murphy plan to control by reportedly issuing nonvoting shares to IPO investors, the ability to snap up their preferred stock symbol may be surprisingly slippery.

Since 2009, the process for claiming stock tickers has gotten much more democratic—both the New York Stock Exchange and the Nasdaq (NDAQ) allow anyone to request one through a simple online form. The cost to claim your own: $0.

Indeed, with just a few clicks, this Fortune reporter put in requests to reserve the tickers SNAP, UBER, LYFT and ABNB—stock symbols that are likely to be in demand if and when certain so-called unicorn companies go public in the coming years.

The stock exchanges say the ticker reservation system is mostly first-come, first-served, with no requirements in terms of revenue, name of the company (and whether it relates to the ticker), or even definite plans to go public. Joseph Brantuk, who heads the new listings and IPOs team at Nasdaq, likens it to staking a claim to a website address before officially launching a business. But unlike with Internet domain names, where speculators squat on many URLs with hopes of selling them to the highest bidder, Brantuk says there’s really no point with tickers: “There’s no value in the symbol,” he says. “There’s no black market.”

The reason: While NYSE and Nasdaq used to “gobble up” bunches of ticker symbols, as Brantuk puts it, in hopes of coercing pre-IPO companies to choose their exchange, there is now a middleman that keeps ticker reservations confidential. The Options Clearing Corporation (or OCC) has since 2009, in accordance with regulatory policy, assumed the additional role of Intermarket Symbols Reservation Authority, essentially acting as the independent keeper of the stock symbols.

That means that a company requesting a ticker symbol could find out if that symbol was already reserved, but not who had reserved it, making it impossible to pay off that party to release it. (Reservations expire in two years if the company does not go public by then.)

For the most hotly anticipated IPOs, though, the exchanges maintain what they call a perpetual list of ticker symbol reservations for companies that they think are likely to want them in the near future. Think of it as akin to restaurants that keep a table perpetually available for certain VIP guests that might drop in. But the exchanges say they’re bound by a “gentleman’s agreement” to give up those symbols if a company wants to use one on the rival exchange.

Plus, adds a NYSE spokesperson, the exchanges use their own discretion when reserving ticker symbols, and would only reserve one on a company’s behalf if “it has a reasonable basis to believe that it will utilize the symbol.”

That likely explains why Fortune is still waiting to hear back if its requested ticker symbols are even available. (Neither Snap, Uber, Lyft nor Airbnb responded to requests for comment, and neither NYSE nor Nasdaq would say whether SNAP was on their perpetual lists.)

Snap probably doesn’t have to worry.

Snapchat is featured on our 2017 roundup of Breakthrough Brands. See the full list here.

A version of this article appears in the January 1, 2017 issue of Fortune with the headline “How to Snag a Stock Ticker.”