An ORDER to purchase or sell securities that must be filled completely or not at all. Allornone orders are often marked FILL OR KILL. See also ALLORANY PORTION ORDER.ALLORNONE UNDERWRITING A NEW ISSUE UNDERWRITING where the issuer has the right to cancel the entire transaction if the SYNDICATE is unable to successfully place the entire issue. See also BESTEFFORTS UNDERWRITING, BOUGHT DEAL.ALLORNOTHING OPTION See BINARY OPTION.
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