The data contract

Fields are added, never removed or redefined

Inside /api/v1/, a field is added and never removed, renamed, retyped or given another meaning. A field kept for compatibility is listed in deprecations.json with what replaces it, and keeps answering for as long as v1 is served. A change that would break a field is published under a new version path, never inside v1.

How to check it: deprecations.json lists what is kept for compatibility; the OpenAPI description types every field; the manifest's schema digest is read from the tables of fields the reference is written from, never from the files' data, and a field, a code or a type added to those tables moves it.

Every holdings figure is dated and sourced

Every fund file names its source (source_layer, and the filing's address for a fund read from SEC filings) and the date of what it states: the date of its holdings (holdings_as_of), or for a fund with no holdings yet the day its prospectus was filed, and the date of its prices (as_of) beside the figures computed from them. Every holder listed in a stock file carries the date of its fund's file or filing. The overlap of a written comparison and the ETF ownership figure name their method, published with its formula and test vectors in methods.json.

How to check it: the build stops before it publishes when a fund file names no source_layer or no date for what it states, and the manifest gives each source's version, date and age in days.

A key follows the listing, and an old key keeps answering

A holding is keyed by the line it is: a US line by its ticker, a line abroad by its local code and its market (7203.JP). A key written before lines abroad carried their market reads as its new keys, in reads_as and in the aliases of the holders shard of its first character. A fund address listed under aliases in deprecations.json answers 301 to the fund's file under its new ticker. A fund read from SEC filings whose ticker the directory of US-listed funds now gives another fund or a company is not served under it, and a figure that was published under the wrong security is recorded in corrections.json, as SPCX and AFIF were.

How to check it: deprecations.json lists every alias the Worker answers, read from its code.

No silent rewrite

A published figure changes for one of three reasons: a newer source file or price, each with its own date; a new version of a method, with a new id in methods.json, or of one of the readers and computations the manifest names under calculation.readers, either of which moves the manifest's calculation version; or a correction, recorded in corrections.json with its date, the families of files it touched, the tickers and what changed. Every night's files are listed with their sha256, so a program that keeps each night's list can tell exactly which files changed between two nights.

How to check it: corrections.json and the manifest's sha256sums.txt.gz; changelog.json for every other dated change.

Private company holdings the funds filed were left out

2026-10-16 · How an issuer file or a filing was read · Files: private-companies · Tickers, for example: ARKK, ARKF, ARKW, DXYZ

Before. A holding counted only when the fund marked it a restricted security or a private placement, filed it as common or preferred stock, gave its series and its value in dollars. ARK Innovation ETF, ARK Next Generation Internet ETF and ARK Blockchain and Fintech Innovation ETF file their OpenAI shares without the mark, BlackRock Private Investments Fund files Anthropic under OTHER, ARK Venture Fund and Destiny Tech100 file without a series, and a row in pounds or euros was dropped although the filing gives its value in dollars: OpenAI was held by 69 funds instead of 83 on the 2026q3 data set, Anthropic by 110 instead of 120.

After. Once two funds hold a company as a marked private placement, a level 3 preferred share of it counts without the mark, and so does any level 3 share of a company whose names the site joins by hand, such as OpenAI and Anthropic, under OTHER too. A fund without a series is its registrant. Every value is the filing's dollars. A fund holding a vehicle that names the company is listed apart, never counted. A report for the first or second month of a fiscal quarter, which is not public, is not read.

A merger was ranked as ETF selling

2026-10-08 · ETF flows · Files: flows · Tickers: BLFS, RGEN

Before. The ETF flows of the first night ranked BLFS among the largest net reductions of the day: the funds' BLFS lines left their files when BLFS merged into RGEN, which read as sales.

After. A corporate action is published as one, dated at the first close where any of its lines were flagged, and its securities leave the rankings of that close.

A fund was served under a ticker that now names a company

2026-10-04 · A ticker reused or moved · Files: fund, sec, holders · Tickers: SPCX, SPCK

Before. The SPAC and New Issue ETF trades as SPCK, and Nasdaq Trader's directory of 2 October 2026 gives SPCX to Space Exploration Technologies' Class A common stock. The SEC's ticker file still gave the fund's series SPCX, so /api/v1/fund/spcx.json served the fund's filing under the company's ticker.

After. The fund is served as SPCK, from the same filing, and SPCX's one file is the company's stock file under /api/v1/sec/. A fund whose every ticker now names a company of another name is refused.

iShares lines under 0.005% were read as 0.00%

2026-10-04 · How an issuer file or a filing was read · Files: fund, sec, holders, compare, history · Tickers, for example: ITOT

Before. iShares prints each weight rounded to two decimals, so a line under 0.005% of a fund read 0.00%: 1,287 of ITOT's 2,448 lines on its file of 1 October 2026, which the overlap figures left out.

After. Each weight is computed from the row's market value, to six decimals, when the market values agree with the printed weights within the rounding. The overlap figures keep 2,440 lines of that file, and ITOT's overlap with VTI's file of 31 August 2026 went from 93.0% to 95.4%. The holdings history reads the step to the first file weighted this way as a restatement, not as trades.

Two fund files were read from the filings of an earlier fund

2026-09-29 · A ticker reused or moved · Files: fund, sec, holders · Tickers: AFIF, GBXB

Before. AFIF and GBXB had fund files built from SEC filings of the series the SEC's ticker file still gave their tickers: AFIF from the filing of Hypatia Women CEO, a fund whose ticker is now Anfield Universal Fixed Income's, and GBXB from a filing of 2025 of a buffer fund no longer listed.

After. A series whose name shares no significant word with the name the directory gives its ticker today, or whose portfolio is more than nine months old, is not served under that ticker. The two files were removed that night.

Preferred stock funds were listed as holders of the common stock

2026-09-28 · How securities are keyed · Files: fund, sec, holders, history · Tickers, for example: JPM, BAC, WFC, GOOGL, PGF, PGX, PFF, PSK, CVY

Before. Most issuer files write a preferred share under its issuer's common ticker, so preferred stock funds were listed among the holders of the common stock: JPMorgan's counted 7 preferred funds and Bank of America's 10.

After. Such a row is keyed as the ticker and .PFD (JPM.PFD), a US line apart from the common stock, and the holders of a common stock are the funds that hold it. Each fund's weights sum as before.

Two companies sharing a local code were added together

2026-09-28 · How securities are keyed · Files: fund, sec, holders, compare, history · Tickers, for example: TM, 7203.JP, 7203.SA, SAN.ES, SAN.FR

Before. A line listed outside the United States was keyed by its local code alone. A fund that held two companies under one code saw them added together (7203 was Toyota in Tokyo and Elm in Riyadh, SAN Banco Santander in Madrid and Sanofi in Paris), and the Malaysia fund, where TM is Telekom Malaysia, was listed as the heaviest holder of Toyota's TM.

After. Each line abroad is keyed by its local code and its market (7203.JP, 7203.SA, SAN.ES, SAN.FR), and US tickers did not change. Each earlier key is listed with the keys it reads as now, under aliases in the holders shard of its first character.

Vanguard weights were inflated

2026-09-26 · How an issuer file or a filing was read · Files: fund, sec, holders, compare · Tickers, for example: VWO, VT

Before. On the files of 24 September 2026: Vanguard weights were normalised over the named rows only, which raised every row: VWO's TSMC read 18.28%. A page limit cut VT's file at about 6,000 rows.

After. Each weight is the row's market value over every row's: VWO's TSMC reads 15.45%, and VT has its 9,451 rows.

Orion S.A. was published as Orion Group Holdings

2026-09-26 · How securities are keyed · Files: fund, sec, holders · Tickers: OEC, ORN

Before. Orion S.A., which every fund that files it writes as OEC, was published as ORN, the ticker of Orion Group Holdings, in 19 funds read from SEC filings, and in 10 of them it was added to their real ORN position.

After. A line is kept under the ticker its filers agree on when that ticker is on the US list: Orion S.A. is OEC, and ORN is Orion Group Holdings alone.

iShares funds of funds summed two tables

2026-09-26 · How an issuer file or a filing was read · Files: fund, sec, holders, compare · Tickers: HEWJ, HEEM, HEZU, HEFA, HAWX, HSCZ, SMMD, CORO

Before. On the files of 24 September 2026: these files hold two tables, the fund's own book and the same book looked through to the stocks, and both were summed: HEZU read 195.5% of its weight.

After. The look-through table is read (HEZU 97.6%), and the fund's own book is kept apart.

Invesco files lost some kinds of rows

2026-09-26 · How an issuer file or a filing was read · Files: fund, sec, holders, compare · Tickers, for example: KBWD, CVY, EELV, PSP, PXH, IMVP, RSPA, QQQ, CGW, CUT, CZA, EEMO, EFAA, ERTH, IDLV, IMFL, IPKW, IQSZ, MTRA, PDN, PEY, PID, PIE, PWV, PXF, PXJ, QEW, QQA, QQI, SOXQ

Before. On the files of 24 September 2026: business development companies, MLPs, NVDRs, preference shares, units and listed trusts were dropped from Invesco's files (KBWD listed 60.1% of its weight, CVY 74.9%), and equity-linked notes were read as the issuing bank's shares: RSPA showed Wells Fargo at 1.72% for a true 0.14%. QQQ had no ASML line.

After. Those rows are read: KBWD lists 99.5% of its weight and CVY 95.0%, the notes are no longer read as bank shares, and QQQ has its ASML line. Between the archived files of 26 and 28 September 2026, 26 Invesco funds gained rows and more than one point of weight, EEMO from 91.0% to 100.6%.

Two spellings of one security were two holdings

2026-09-07 · How securities are keyed · Files: fund, sec, holders, compare · Tickers, for example: BRK.B, BRKB, IVV, SPY

Before. Issuers spell some securities differently, so BRKB and BRK.B were two holdings, and the overlap of two funds of two issuers was understated: IVV against SPY read 97.8%.

After. Each security has one spelling across issuers, settled when the holdings are stored, and two spellings whose issuer names share no word stay two securities. IVV against SPY reads 99.2%, and 13 other pairs of funds of two issuers moved with it.

Some holdings dates were in the issuer's own format

2026-09-03 · How an issuer file or a filing was read · Files: fund, holders · Tickers, for example: SPY

Before. 93 holdings dates were written as the issuer writes them, so SPY's read 02-Sep-2026 beside QQQ's 2026-09-02.

After. Every date is written YYYY-MM-DD.