Ah ok, i see. Is the premium already payed/set in advance by the way? This way, its a gamble to pay for these rights to buy stocks at $115 (risk-reward as you mentioned)?No, you pay the call price. And that's what makes it worthwhile. You buy for 115, the stock price is 300. You can immediately sell for 300 and pocket the difference. The thing is, you pay a premium (depends on the share price, and per share) to acquire the call. So if the share price is below 115, you don't exercise the call (because why would you) and you lost your up-front payment. That's the risk-reward of calls.
Mostly the broker from which you bought the call holds the actual share(s), to then sell to you when you exercise the call. So in that sense, they can then sell the share because they don't need to hold it for you.
And now that these rights have expired today, what will the brokers do with the held stocks? Sell them on the open market to anyone?