Busy week for US offerings

UP to six companies will try to go public this week, in what could be the US&rsquo;s busiest week of the year for initial public offerings.<br /><br />The IPOs include a $520m (&pound;310m) offering on the New York Stock Exchange from coal mining company Cloud Peak Energy and a $69m deal from national security specialist Global Defense Technology &amp; Systems. <br /><br />Three technology companies are keen to list on the Nasdaq; Global Defense, medical record management firm HealthPort and computer network security company Fortinet.