X0303 4 2011-03-16 0 0000873044 RADISYS CORP RSYS 0001282683 Nierenberg Investment Management Company, Inc. 19605 NE 8TH STREET CAMAS WA 98607 1 0 1 0 0001040899 Nierenberg David 19605 NE 8TH STREET CAMAS WA 98607 0 0 1 0 0001282685 D3 Family Fund, LP 19605 NE 8TH STREET CAMAS WA 98607 0 0 1 0 0001365745 D3 Family Bulldog Fund, LP 19605 NE 8TH STREET CAMAS WA 98607 0 0 1 0 0001405824 D3 Family Canadian Fund, LP 19605 NE 8TH STREET CAMAS WA 98607 0 0 1 0 Stock Options (Right to pruchase) 2011-03-16 4 A 0 1300 A 2018-03-16 Common Stock 1300 1300 I The D3 Family Fund, LP Stock Options (Right to pruchase) 2011-03-16 4 A 0 5100 A 2018-03-16 Common Stock 5100 5100 I The D3 Family Bulldog Fund, LP Stock Options (Right to pruchase) 2011-03-16 4 A 0 600 A 2018-03-16 Common Stock 600 600 I The D3 Family Canadian Fund, LP The stock options have an exercise price of $8.11. David Nierenberg was appointed to the Board of Directors of the issuer effective March 16, 2011. In connection with his appointment, Mr. Nierenberg was granted 7,000 stock options, which vest as follows: (a) One-third of the total option shares shall vest and be exercisable after one year, and (b) thereafter, in equal monthly increments over the two succeeding years. These stock options are held for the benefit of the reporting persons identified above in Table II of this Form 4. Additionally: (a) The D3 Family Fund, L.P. owns 727,510 shares of common stock, (b) The D3 Family Bulldog Fund, L.P. owns 2,742,682 shares of common stock, (c) The D3 Family Canadian Fund, L.P. owns 256,095 shares of common stock, and (d) The DIII Offshore Fund, L.P. owns 801,176 shares of common stock. Each of the reporting persons disclaims beneficial ownership of these securities except to the extent of the reporting person's pecuniary interest therein. David Nierenberg, President, Nierenberg Investment Management Company, Inc. (NIMCO) 2011-03-17 David Nierenberg, President, NIMCO, General Partner of The D3 Family Bulldog Fund, LP 2011-03-17 David Nierenberg 2011-03-17 David Nierenberg, President, NIMCO, General Partner of The D3 Family Canadian Fund, LP 2011-03-17 David Nierenberg, President, NIMCO, General Partner of The D3 Family Fund, LP 2011-03-17