But some market commentators believe we must be heading for a top.
The signs are there if you want to look for them. As of yesterday, the Dow had erased all of 2014's gains. Forward price-to-earnings ratios are well above both their 5- and 10-year averages. Even Alan Greenspan has said a correction is inevitable given that the rally is now well into its fifth year.
There are other, less technical signs.
We've pinpointed the 15 most ridiculous moments in finance of the year so far that might lead one to believe that bull markets are dangerously low on oxygen.