Sept. 23 1999 3:30 AM

When Hillary Clinton began exploring a campaign for the U.S. Senate in New York, pundits anointed her the clear favorite. Some suggested that New York Mayor Rudy Giuliani should back out and wait for a better shot at higher office. But the polls haven't borne out that bullishness about Clinton--one recent poll has her tied with Giuliani, while another has her trailing by nine points--and the Iowa market is even more skeptical. Clinton's share price hasn't reached 40 cents since July 21, and Giuliani's hasn't fallen below 50 cents since Aug. 13. This weekend, Giuliani's stock was worth nearly twice Clinton's. Do the pundits know something the investors don't? Or is it the other way around?