Graviex is a Malta-registered centralized crypto-exchange rated #113 at Coingecko with daily trading volume of about 10 BTC. The exchange trades all main pairs (BTC, LTC, ETH, DASH, USDT, USDC, etc) and quite a lot of small altcoins.

That's especially good about Graviex is that it pays hourly dividends to clients depending on the total trading volume at the exchange. Even better is that the dividends are paid in BTC satoshis, not tokens, altcoins, points or something.

To get paid you simply must hold some amount of the exchange's native coin Graviocoin (GIO) on your account.

There's neither minimum amount to hold nor "locking period" or similar, the coins are kept on your trading account and can be traded or withdrawn at any time.

However, the smallest lot at GIO/BTC is about 1000 GIO (depending on current GIO/BTC price) and there's little use to hold small amounts (say, less than 1000 GIO) because dividends will be too small to be paid.

Calculation of dividends is: ((Trading volume within BTC market * percentage rate of dividends) / total value of gained coins) * quantity of available coins at your GIO account. Calculation of dividends depending upon a user’s GIO balance is processed every hour during the first 5 minutes of an hour. ... BTC acquired as calculated dividends is deposited at a trade account once a day (the amount to be deposited is not less than 0,1 satoshi). 

You can guess the approximate amount of dividends with the calculator  (note that the actual amount of dividends may vary and depends not only on how many GIO you have on account, but also on total amount of GIO in circulation, current GIO/BTC price, total trading volume of the exchange, etc).

Pros of holding GIO at Graviex :

• easy to get tokens (buy or mine) and stake them
• dividends are paid daily and are ready for trading or withdrawal, no "lock", "freeze", etc.
• dividends are paid in real bitcoins BTC

Cons :

• you can't expect triple-digits annual returns, all the more in BTC
• you can't predict the exact number of dividends, even for the current day
• GIO/BTC is traded in lots, you can't buy 1 GIO compounding your earning (however, it's still possible to buy 1 GIO against an altcoin).

Disclaimer: I'm not an employee or otherwise affiliated with the exchange. This article is informational and not a financial advice or guarantee of any kind. I myself own a small amount of GIO at Graviex