Hydroxide
Hydroxide is a diatomic anion with chemical formula OH. It consists of an oxygen and hydrogen atom held together by a covalent bond, and carries a negative electric charge. It is an important but usually minor constituent of water. It functions as a base, a ligand, a nucleophile, and a catalyst. The hydroxide ion forms salts, some of which dissociate in aqueous solution, liberating solvated hydroxide ions. Sodium hydroxide is a multi-million-ton per annum commodity chemical. A hydroxide attached to a strongly electropositive center may itself ionize, liberating a hydrogen cation (H), making the parent compound an acid.
Ticker symbol
Symbols sometimes change to reflect mergers. Prior to the 1999 merger with Mobil Oil, Exxon used a phonetic spelling of the company "XON" as its ticker symbol. The symbol of the firm after the merger was "XOM". Symbols are sometimes reused. In the US the single-letter symbols are particularly sought after as vanity symbols. For example, since Mar 2008 Visa Inc. has used the symbol V that had previously been used by Vivendi which had delisted and given up the symbol.