NY to Ease; Spotlight on Insurers  LONDON (Reuters) - Wall Street was set to start softer on  Thursday with the insurance sector in the spotlight again after  American International Group &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=AIG.N target=/stocks/quickinfo/fullquote"&gt;AIG.N&lt;/A&gt; said it was being probed  by a federal grand jury.