A superb post by NY Fed’s Liberty Blog.
The term “bear” dates back to 1709, when it was used as shorthand for the bearskin jobber occupation. The title “bearskin jobber” originates from a proverb highlighting the practice of selling bearskins before catching the bear. In a more modern sense, a bear is someone who expects prices to fall, thus selling stocks in hopes of a future compensation.
The bull and bear as visual symbols may have entered the public consciousness with Thomas Nast’s cartoon in Harper’s Weekly after the crash of 1869 in which dead bulls and a bear (and for some reason a fox and other cute animals) are shown in a heap in front of a roped-off Wall Street with a sign reading “This ‘Street’ is closed for repairs” and a caption stating “What a fall was there, my countrymen!”