Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

Does the “Free Ride” rule always apply to your entire collection of shares in a particular stock?
You should check with your broker for details, but you can generally specify which "lot" you are selling.  where I've seen it, that's done by concurrently sending a "letter of instruction" documenting your choice of lot concurrent with the sale, but different brokers may handle this differently.  I would think this should work for the case that you describe. (In addition, the default rule used by your broker is "probably" first-in-first-out, which will do what you want here.) Note that this may come into play even in a margin account to the extent that you might want to specify a lot in order to obtain (or set yourself up for later benefit of) favorable tax treatment under the long-term capital gains rules