Bombardier CEO Quits, Shares Dive  MONTREAL (Reuters) - Paul Tellier stepped down on Monday as  president and chief executive of Bombardier Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=BBDsvb.TO target=/stocks/quickinfo/fullquote"&gt;BBDsvb.TO&lt;/A&gt;  &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=BBDb.TO target=/stocks/quickinfo/fullquote"&gt;BBDb.TO&lt;/A&gt;, surprising investors and sending the train and plane  maker's shares down as much as 26 percent to a 10-year low.