September is a time for investors to be more cautious, says Jeff McClean, pointing out "a lot of headwinds coming" for the stock market. The month is starting on shaky ground as crude oil and Treasury yields climb. Jeff notes a mixed picture for the Fed as well with Kevin Warsh establishing independence despite a lack of interest rate guidance. As far as stocks Jeff is watching, he tells investors to wait until SpaceX's (SPCX) lockup period ends and sees more room to run for Marvell (MRVL).