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What is the meaning of “writing put options”?
Apple closed Friday 9/23 at $403.40.   This is what the Puts look like, note the 2013 expiration.  (The rest is hypothetical, I am not advising this.) As a fan of Apple and feeling the stock may stay flat but won't tank, I sell you the $400 put for $64.65.  In effect I am saying that I am ready willing and able to buy aapl for $400 (well, $40,000 for 100 shares) and I have enough margin in my account to do so, $20,000. If Apple keeps going up, I made my $6465 (again it's 100 shares) but no more. If it drops below $400, I only begin to lose money if it goes below $335.35.  You, the put buyer are betting it will drop by this amount (more than 15% from today) and are willing to pay the price for this Put today.