--- title: What Is AUM? The Three Numbers That Get Called the Same Thing type: learn slug: what-is-aum-assets-under-management-13f-guide canonical_url: https://13finsight.com/learn/what-is-aum-assets-under-management-13f-guide published_at: 2026-05-17T15:31:59.496Z updated_at: 2026-05-17T15:32:03.457Z author: Sarah Mitchell author_title: Education Editor author_url: https://13finsight.com/authors/sarah-mitchell word_count: 1106 locale: en source: 13F Insight --- # What Is AUM? The Three Numbers That Get Called the Same Thing > Assets under management means different things in different contexts: the firm's marketing number, the Form ADV regulatory number, and the 13F reported value are not the same. This explainer walks through what 13F AUM actually measures, and the five misreadings that get retail investors into trouble. Assets under management — usually shortened to AUM — is the headline number you see on every fund profile. It is also one of the most frequently misread metrics in institutional research. AUM as reported in a 13F filing is not the same as the AUM marketed in a hedge fund's prospectus, and it is not the same as the firm's "managed money" in any economic sense. This explainer walks through what AUM actually measures in different contexts, how to read it from a 13F filing on 13F Insight, and the five misreadings that get retail investors into trouble. The three different "AUMs" you'll encounter The word "AUM" gets used to describe three different things, and they don't agree: 1. Marketing AUM (firm-level) This is the number the firm publishes on its website or shareholder letters. It typically includes: All long equity positions All long fixed-income positions Cash and money-market reserves Short positions (sometimes counted as positive exposure, sometimes netted) Off-balance-sheet exposures via derivatives Discretionary and non-discretionary accounts the firm manages Marketing AUM is firm-defined and not standardized. Two firms with the same economic exposure can report wildly different AUM depending on how they count derivatives and shorts. 2. Regulatory AUM (Form ADV) Registered investment advisers file Form ADV with the SEC and report a regulatory AUM that follows a defined formula. Form ADV AUM is closer to "managed money" but still has quirks: it includes uncalled capital commitments for private funds and treats client accounts under continuous supervision as part of the total. 3. 13F AUM (Form 13F reported value) This is the number you'll see on a 13F Insight filer page. It is the sum of the market value of all reportable Section 13(f) securities held by the institutional manager at quarter-end. It includes: U.S.-listed equities ADRs Closed-end funds ETFs (sometimes) Convertible notes and equity-linked instruments Long option positions (reported at notional value, not premium) It does NOT include: Short positions (13F is a long-only disclosure) Cash and money-market holdings Foreign-listed securities Bonds and most fixed-income Private investments Currencies, commodities, futures The 13F number is what 13F Insight uses everywhere, because it is the only one with a consistent, auditable definition across all 6,000+ filers on the platform. How to read 13F AUM on the platform On any filer page (see Berkshire Hathaway or Citadel Advisors as examples), the headline "Total Value" or "Portfolio Value" is the sum of the most recent 13F filing's reportable positions, marked to the report date (the last business day of the quarter). The history sparkline shows how that number has evolved quarter over quarter. To check the underlying composition, scroll to the holdings table. The sum of the "Value" column across all rows equals the headline number — every dollar of 13F AUM is allocated to a specific line item. There is no "other" or "miscellaneous" bucket. If a position has $0 value because of a join issue between the holdings table and the securities table, the filer's total will be off by that amount; the platform tracks and remediates this case (see the case-sensitive CUSIP join fix from April 2026). The five misreadings to avoid Misreading 1: Treating 13F AUM as economic AUM If you see a hedge fund's 13F value at $50 billion, that is not necessarily their managed money. A pair-trading long-short fund with 200% gross exposure (100% long, 100% short) will show $50 billion of 13F long positions backed by only $25 billion of investor capital. The 13F is silent on the short book. Misreading 2: Confusing market-maker 13F value with managed assets Market makers — Citadel Securities, Jane Street, Susquehanna, Optiver, Virtu, Two Sigma Securities — file 13Fs because they hold reportable equity inventory. Their 13F can show tens or hundreds of billions of dollars, but this inventory is hedged against derivative positions and is not "managed money" in any traditional sense. The institutional signal feed filters market makers out of smart-money surfaces by design. Don't include them in AUM comparisons or "top investor" rankings without flagging the business model. Misreading 3: AUM growth = performance A fund's 13F AUM can grow for two distinct reasons: the existing positions went up in price, or new capital was added (or both). 13F filings do not separate the two. To gauge actual performance, compare the share-count change across positions, not the value change. If share counts stayed flat across the book and value rose 20%, that's market beta. If share counts rose materially across the book, the fund raised capital. Misreading 4: Confusing 13F filer AUM with fund-vehicle AUM A large investment company might run a dozen separate funds — equity, credit, macro, real estate — but file a single consolidated 13F for the equity sleeve. A $100 billion 13F at the firm level does not mean the firm runs $100 billion of equity capital; it might mean the equity sleeve is $30 billion of capital with leverage and the rest is non-13F asset classes. Always cross-check with Form ADV for the regulatory-AUM number when sizing a fund. Misreading 5: Index-fund AUM as conviction The largest 13Fs on the platform are filed by Vanguard, BlackRock Fund Advisors, State Street, Geode, and similar passive index complexes. Their AUM is mechanically driven by ETF inflows and index reweighting — they own everything in the relevant index in proportion. Including them in any "top conviction holders" ranking is a category error. The platform classifies passive index funds, market makers, and custodians separately so the active-manager signal is clean. A worked example Imagine Filer A reports $20 billion in 13F value, with 25 line items, top holding 18% of the portfolio. Filer B reports $200 billion, 1,500 line items, top holding 0.7% of the portfolio. Both could be called "$20B" and "$200B" investors in casual writing, but they are not comparable institutions. Filer A is a concentrated active manager. Filer B is almost certainly a diversified index complex or a quasi-passive vehicle. The AUM number alone tells you almost nothing; the structure of the portfolio (concentration, line-item count, filer type) tells you everything. What to read instead of AUM in isolation If you find yourself comparing two filers by AUM, also compare: Holdings count — a proxy for diversification Top-10 concentration — proxies for active conviction Filer type — active manager vs. passive index vs. market maker Quarter-over-quarter change in share counts — true activity vs. price drift The smart-money signal feed rolls those metrics up across the active-manager universe. The consensus tool uses them to identify where conviction concentrates, not just where dollars sit. AUM is the headline number, but the productive read is always one layer deeper. ## FAQ ### What does AUM stand for in finance? AUM stands for Assets Under Management — the total market value of investments a firm manages on behalf of clients. In 13F context, it specifically refers to the total reported value of Section 13(f) securities held by the institutional manager at quarter-end, marked to the report date. ### Why is 13F AUM different from a hedge fund's marketing AUM? 13F AUM only includes reportable long equity positions, ADRs, ETFs, and long options at notional value. It excludes shorts, cash, fixed income, foreign-listed securities, and private investments. A hedge fund's marketing AUM typically includes all of these plus uncalled capital commitments and derivative exposures. ### Does a higher 13F AUM mean a better fund? Not directly. AUM can grow because positions went up in price or because new capital was added — 13F filings do not separate the two. To gauge real activity, compare share-count changes across positions, not just value changes. AUM size alone says nothing about strategy quality, concentration, or performance. ### Why does Citadel Securities have a huge 13F AUM? Citadel Securities is a market maker. Its 13F filing reports hedged equity inventory used to facilitate client trades, not managed investment capital. The 13F Insight platform classifies market makers separately and excludes them from smart-money surfaces because their positions reflect hedged inventory, not investment conviction. ### Why are Vanguard and BlackRock the largest 13F filers? Vanguard, BlackRock Fund Advisors, State Street, and Geode are passive index complexes. Their AUM is mechanically driven by ETF inflows and index reweighting — they own every name in the index in proportion. Including them in 'top conviction holder' rankings is a category error. The platform classifies passive index funds separately. ### Where do I see a filer's 13F AUM on 13F Insight? Open any filer page (such as /filers/berkshire-hathaway-inc-0001067983) and the headline 'Total Value' or 'Portfolio Value' equals the sum of the most recent 13F filing's reportable positions. The history sparkline shows the trajectory quarter over quarter, and the holdings table breaks the AUM down to every line item. ### Can two firms with the same AUM be completely different investors? Yes. A $20B 13F with 25 line items and an 18% top holding is a concentrated active manager. A $20B 13F with 1,500 line items and a 0.7% top holding is a quasi-passive vehicle. The AUM number alone tells you almost nothing — the structure of the portfolio (concentration, line-item count, filer type) is the productive read. --- Source: 13F Insight — https://13finsight.com/learn/what-is-aum-assets-under-management-13f-guide Author: Sarah Mitchell — https://13finsight.com/authors/sarah-mitchell Last updated: 2026-05-17T15:32:03.457Z