X0305 4 2012-06-26 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 Restricted Stock Units 2012-06-26 4 A 0 1620 A Common Stock 1620 2937 I The D3 Family Fund, LP Restricted Stock Units 2012-06-26 4 A 0 5320 A Common Stock 5320 10993 I The D3 Family Bulldog Fund, LP Restricted Stock Units 2012-06-26 4 A 0 560 A Common Stock 560 1237 I The D3 Family Canadian Fund, LP David Nierenberg is a member of the Board of Directors of the issuer. As a director, Mr. Nierenberg was granted 7,500 restricted stock units on June 26, 2012 which vest 50% per year on the anniversary of the grant date. These restricted stock units are held for the benefit of the reporting persons identified above in Table II of this Form 4. Each restricted stock unit represents a contingent right to receive one share of the issuer's common stock. One share of common stock will be automatically delivered to the reporting person for each restricted stock unit that vests. Additionally: (a) The D3 Family Fund, L.P. owns 728,293 shares of common stock and 1,300 stock options, (b) The D3 Family Bulldog Fund, L.P. owns 2,745,429 shares of common stock and 5,100 stock options, (c) The D3 Family Canadian Fund, L.P. owns 256,398 shares of common stock and 600 stock options, 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) 2012-06-28 David Nierenberg, President, NIMCO, General Partner of The D3 Family Bulldog Fund, LP 2012-06-28 David Nierenberg 2012-06-28 David Nierenberg, President, NIMCO, General Partner of The D3 Family Canadian Fund, LP 2012-06-28 David Nierenberg, President, NIMCO, General Partner of The D3 Family Fund, LP 2012-06-28