Think of the strike as what you have the option to pay to get the deliverable (usually 100 shares of the stock). So, pre-spinoff, by owning 1 contract of the $70 strike calls you have the option to pay $7000 (there's a 100 multiplier) to buy 100 shares of EBAY.
If EBAY spins off 1 share of PAYPAL for each share of EBAY, the deliverable of the options contract will be adjusted to represent 100 shares of EBAY -plus- 100 shares of PAYPAL. So, you would have the option to pay $7000 to purchase 100 shares of EBAY and 100 shares of PAYPAL.
Within a day or so, they will then list a new series of options contracts that will just represent 100 shares of EBAY. At this point, if a person wanted to buy options on just pure (post spinoff) EBAY they would be able to do so. But the old series of options sticks around, so there will likely exist two EBAY $70 2017 calls - the old ones (100 EBAY + 100 PAYPAL) and the new ones (100 EBAY). It will be important to make sure you are trading the right ones if you want to do new trades.
Thank you both for your contributions.
I guess the OCC (Options Clearing Corporation) to set the strike for the Ebay's new options will be taken into account:
- or the opening trading price of the shares of Ebay as independent entity (after split).
- or the closing price of the first day as a independent Ebay.
I will consult with the OCC to see if I can still clarify a little bit more this things.
I'll keep you informed,
By the way, according to your nick (pocoapoco) I think you're from a Spanish-speaking country. Is that so? I'm from Spain.