Changing toNasdaq Registery, page-8

May be contradictory advice
From
US Taxation Implications
http://www.investopedia.com/ask/answers/06/nonusresidenttax.asp
If you fall under the non-resident alien category and the only business you have in the U.S. is in investments (stocks, mutual funds, commodities) within a U.S. dollar-denominated brokerage firm or other agent, you are subject to the following tax guidelines. In terms of capital gains, non-resident aliens are subject to no U.S. capital gains tax, and no money will be withheld by the brokerage firm. This does not mean, however, that you can trade tax free - you will likely need to pay capital gains tax in your country of origin.

DYOR-read and interpret yourself- get proper taxation advise- only speculation on my part.
Don't blame me if you get it wrong