Definition
A contango is the premium or fee paid by a buyer to a seller on the London Stock Exchange to defer the settlement of a stock transaction from the current settling day to the next. Rather than paying for purchased shares immediately or on the current account day, the buyer compensates the seller for the delay through this charge, effectively purchasing more time before the transfer of stock and payment must be completed.
The term belongs to the mechanics of the London Stock Exchange's historical account system, under which share transactions were settled periodically — typically on fortnightly settling days — rather than on a continuous rolling basis. A buyer who was unable or unwilling to complete settlement on the approaching account day could "carry over" the transaction to the next settling day by paying the contango rate to the seller.
Common Language
Modern common usage (Wiktionary): To charge a buyer a fee to defer settlement until the next settlement day.
Historical common usage (Webster's 1913): The premium or interest paid by the buyer to the seller to defer paying for stock purchased until the next fortnightly settlement day; the postponement of payment by the buyer on payment of a premium to the seller. See Backwardation.
Editorial note: The common and legal definitions are closely aligned — contango originated as a market practice term before appearing in legal dictionaries, and its legal meaning has never meaningfully diverged from its financial market meaning. Modern financial usage has, however, extended "contango" to describe a futures market condition in which future delivery prices exceed spot prices, a broader and more abstract sense the legal definition does not reach.
Common Confusion
Contango and backwardation are paired opposites in the historical London Stock Exchange account system. Contango is the premium paid by the buyer to carry over a purchase to the next settling day; backwardation is the premium paid by the seller to defer delivery of stock already sold. Researchers encountering one term in historical securities law sources should expect the other nearby. In modern commodities and derivatives markets, both terms have been repurposed with related but technically distinct meanings referring to price curve structures across delivery dates. Legal sources using these terms in a commodities futures context are not using them in the historical English stock exchange sense.
Why It Matters in Research
Contango is a term almost entirely confined to English law and specifically to the rules and practices of the London Stock Exchange. American legal sources rarely use it, and when they do, they are either describing English law directly or citing Wharton's Law Lexicon as their authority — as all four historical dictionary entries here do.
Researchers working in late nineteenth or early twentieth century English securities law, stock exchange regulation, or commercial law will encounter contango in discussions of account day mechanics, carrying-over agreements, and the liabilities that arose from deferred settlement. Because the London Stock Exchange operated on a periodic account system rather than rolling daily settlement, an entire body of case law and exchange rules developed around the rights and obligations created when buyers carried over positions through contango arrangements.
The critical research trap: modern financial and commodities law uses "contango" to mean something categorically different — a market structure in which forward prices exceed spot prices. If a legal document postdates the shift to continuous settlement practices (broadly, the late twentieth century), contango almost certainly carries the modern commodities sense, not the historical stock exchange sense. These two meanings are not interchangeable and should not be read as if they were.
Corpus connections: contango appears in Law Mind sources alongside backwardation, account day, settling day, jobber, and stock exchange rules generally. Its presence signals English commercial law context. Researchers using it as a search term in historical corpora should note that early sources may spell or hyphenate it inconsistently.
Historical Dictionary Support
All four historical dictionaries in the Law Mind corpus converge on a single definition, and all trace their authority to Wharton's Law Lexicon. This convergence signals that the term had a settled, uncontested meaning within English legal usage and that the dictionaries were transmitting rather than independently analyzing it.
Rapalje & Lawrence is the most informative of the four, offering the only entry that contextualizes the definition within the mechanics of the London Stock Exchange account system — explaining the distinction between ready money contracts and time contracts, the role of the account day, and the price structure for stock sold to be transferred on the next settling day. This background is essential to understanding what contango actually governed in practice, and its absence from the Black's and Bouvier's entries is a meaningful gap.
None of the historical dictionaries address the carrying-over transaction from the seller's perspective, the legal consequences of default on a contango arrangement, or the exchange rules that governed disputes — subjects a researcher would need to pursue through English case law and the rules of the London Stock Exchange directly.
Jurisdictional Note
Contango in its historical legal sense is an English law term. It has no significant independent legal history in American, Scottish, or Commonwealth jurisdictions, though the underlying practice existed in other exchanges under varying names and rules. American legal researchers encountering the term in domestic sources should treat it as a reference to English law unless context indicates otherwise.