Former U.S. Treasury Secretary Lawrence H. Summers, a Wall Street Week contributor and adviser to President-elect Joe Biden's campaign, says fiscal stimulus will play a role in understanding where markets go from here. Steve Rattner, Willett Adviors chairman and chief executive officer, says the rotation out of tech stocks could signal markets are becoming efficient again. Willett Advisors manages the personal and philanthropic funds of Michael R. Bloomberg, founder and majority owner of Bloomberg. They join David Westin on "Bloomberg Wall Street Week." (Source: Bloomberg)