Finance Glossary R to W: Plain-English Definitions

About this page

Finance is full of terms that sound simple until you have to use them. This page is a plain-English glossary for Finance Encyclopedia, covering entries such as Rate base, Rate on line, Rater effect, Rational expectations, Realized spread, each with a short definition and a pointer to the part of the volume where it is explained.

Keep it open while you read, or use it to settle an argument about what a term really means. Every entry is written to stand on its own, with no jargon left undefined, and the part number beside it tells you where to read more. Use it as a quick reference whenever a term trips you up.

A sample of the entries (51 terms on the full page)

Rate base — A regulated utility’s invested capital less accumulated depreciation, on which the regulator allows a return (Part 2.6).

Rational expectations — The assumption that people forecast using all relevant information and an accurate model, so their errors are not systematic; formulated by Muth (1961). (Part 9.7)

Reconciliation — The process of comparing two independent records of the same activity, such as an internal ledger and a custodian statement, and investigating and resolving every difference. (Part 8.1)

Reference point — The benchmark, such as the status quo, a purchase price or an expectation, from which prospect theory codes outcomes as gains or losses (Part 6.2).

Retrocession — Reinsurance bought by reinsurers to limit their own concentrations and catastrophe losses (Part 1.7).

Risk pooling — Combining many similar risks so that each participant pays a small premium and the pool pays the few who suffer a loss (Part 1.1).

Rollover risk — The risk that maturing debt must be refinanced at higher rates or cannot be refinanced at all; it rises with the share of short-term debt. (Part 3.2)

Scope 1 emissions — Direct greenhouse gas emissions from sources a company owns or controls, such as its boilers, vehicles and processes (Part 7.1).

Scope 3 emissions — All other indirect emissions in a company’s value chain, upstream and downstream, in 15 GHG Protocol categories; usually the largest and least precise share (Part 7.1).

SFDR — The EU Sustainable Finance Disclosure Regulation, whose Article 8 and Article 9 categories are being replaced by a proposal still under negotiation as of October 2026 (Part 7.6).

Special servicer — The firm that takes over a defaulted or troubled CMBS loan and decides whether to extend, modify, sell or foreclose (Part 2.4).

Statutory trust — The trust under which a UK firm holds client money (CASS 7.17.2R), keeping it outside the firm’s estate if the firm fails. (Part 8.1)

Stock record — A firm’s double-entry ledger of securities, recording each holding by owner and by location, with the two sides balancing for every security. (Part 8.2)

Stop-out yield — The highest yield accepted in a Treasury auction; in a single-price auction every winning bidder receives it. (Part 3.2)

Structural deficit — The deficit that would remain with the economy at full employment, after removing the effect of automatic stabilizers; it does not close on its own as the economy recovers, so closing it takes policy action. (Part 3.4)

Substance-based income exclusion — The Pillar Two carve-out of a percentage of payroll and tangible assets from the profit subject to top-up tax (9.4% and 7.4% for 2026, falling to 5%) (Part 4.6).

Sustainability performance target (SPT) — The pre-agreed level a sustainability KPI must reach by an observation date in a sustainability-linked loan or bond (Part 7.5).

Tail factor — A development factor applied beyond the last age in a loss triangle to capture claims development still to come (Part 1.4).

Tax-loss harvesting — Selling investments at a loss to realize capital losses that offset gains and up to $3,000 a year of ordinary income in the US (Part 6.7).

Tested party — The party to an intra-group transaction whose results are compared with independent companies under TNMM or the comparable profits method; normally the simpler entity (Part 4.3).

Tolerance — A preset difference below which items are matched automatically; it belongs on amounts only, never on quantities or identifiers. (Part 8.4)

Undertaxed profits rule (UTPR) — The Pillar Two backstop under which other countries where a group operates collect remaining top-up tax, typically by denying deductions (Part 4.6).

Value function — Prospect theory’s scoring of gains and losses: concave for gains, convex for losses and kinked at the reference point (Part 6.2).

Vostro — “Yours”: another bank’s account held with this bank; the same account as the other bank’s nostro. (Part 8.2)

Wash-sale rule — The US rule that disallows a loss if substantially identical securities are bought within 30 days before or after the sale (Part 6.7).