H

1. The symbol for the element hydrogen.
2. The symbol for enthalpy.

A Nasdaq stock symbol specifying that it is the second preferred bond of the company.

Investopedia Says:
Nasdaq-listed securities have four or five characters. If a fifth letter appears, it identifies the issue as other than a single issue of common stock or capital stock.

The symbol for the element hydrogen.

Chemical symbol, hydrogen; [L.] hora (hour).