The latest development comes after Hynix, the world's second-largest DRAM maker, pleaded guilty in the same case and agreed to pay a $185 million criminal fine last year.
In the ongoing Department of Justice (DoJ) investigation, four companies and nine individuals have been charged with fines totaling more than $731 million.
Hynix participated in the price-fixing conspiracy from 1999 to 2002 by participating in meetings, conversations and other communications in the United States and elsewhere, according to court documents.
The latest to plead guilty today were D.S. Kim, general manager of Hynix Worldwide Sales and Marketing; C.K. Chung, the company's director of Global Strategic Account Sales; K.C. Suh, Hynix's senior manager of Memory Product Marketing; and C.Y. Choi, general manager for Marketing and Sales Support in Hynix's German subsidiary.
Kim was sentenced to eight months of prison time; Chung, seven months; Suh, six months; and Choi, five months. In addition, each executive was fined $250,000 and agreed to cooperate in the international probe.