Thanks for that Coach. I deal with CIBC Wood Gundy and, late in the process, I just looked at a monthly statement to find that each of my holdings is marked with an "s." That means that they are "segregated" rather than being held "in custody" and a footnote in the statement reads "Securities held in custody are registered in your name. Segregated securities are registered in the name of CIBC World Markets Inc. Whether your securities are held in custody or are segregated we do not use them for our business."

That would mean to me that the broker would not use my shares in any short selling transaction. I guess. I hope.