X0303 4 2009-06-16 0 0000924383 AMERICAN TECHNOLOGY CORP /DE/ atco 0001044321 MARXE AUSTIN W & GREENHOUSE DAVID M C/O SPECIAL SITUATIONS FUNDS 527 MADISON AVENUE, SUITE 2600 NEW YORK NY 10022 0 0 1 0 Common Stock 2009-09-16 4 S 0 150000 2.0708 D 3299081 I By Limited Partnership Common Stock 2009-09-16 4 S 0 1900 2.25 D 3297181 I By Limited Partnership Common Stock 2009-09-16 4 S 0 100000 2.298 D 3197181 I By Limited Partnership This is a joint filing by Austin W. Marxe (Marxe) & David M. Greenhouse (Greenhouse). They share voting and investment control over all securities owned by Special Situations Fund III QP, L.P. (QP), Special Situations Private Equity Fund, L.P. (PE), Special Situations Technology Fund, LP (Tech) & Special Situations Technology II, Fund, L.P. (Tech II), respectively. 1,459,791 shares of Common Stock are held by QP, 510,425 shares of Common Stock are held by PE, 170,038 shares of Common Stock are held by Tech and 1,056,927 shares of Common Stock are held by Tech II. The interest of Marxe and Greenhouse in the shares of Common Stock owned by QP, PE, Tech, and Tech II is limited to the extent of his pecuniary interest. Austin Marxe 2009-09-18 David Greenhouse 2009-09-18