(ShareCast News) - Ultra Electronics said it completed the acquisition of the electronics division of Kratos Defense & Security Solutions.The FTSE 250 listed firm paid $265m in cash for what was its largest acquisition to date.Ultra said in an announcement its acquisition had received US regulatory approval and was completed.The acquisition would be renamed Ultra Electronic Herley and operate within Ultra's communications and security division.Shares in Ultra were down by 1.27% to 1706p at 0823 BST.