Mongo Funds: Trade Synthetic Funds Built From the Biggest 13F Filings

Published September 7, 2026 · MongoTrader Team

Every quarter, the largest investment firms disclose what they hold. Mongo Funds turn those public 13F filings into six synthetic tickers you can buy, chart and hold in a MongoTrader portfolio — simulated money, real market data, and a clear view of how a famous book actually moves.

Reading a 13F filing is one thing. Holding the portfolio it describes, watching it mark to market every day, and finding out whether you'd have the stomach for its drawdowns is another. Mongo Funds exist to close that gap. Each one is a synthetic fund ticker built on MongoTrader from the latest public 13F-HR filing of a well-known investment firm. You trade it like any other symbol, with simulated money, and it moves with the disclosed holdings of the manager it tracks.

What a Mongo Fund is

A Mongo Fund is a tradable symbol whose holdings mirror a firm's most recent 13F-HR filing with the SEC. Institutional investment managers file the 13F-HR every quarter, and it is due within 45 days after the quarter ends, so it is a public record of what a manager's long book looked like on a specific date. MongoTrader takes that filing, maps each holding to a ticker it already prices in real time, and publishes the result as a single fund with its own price, chart and detail page.

The funds carry M-prefixed tickers so they sit alongside ordinary stocks in search, in charts and in your portfolio, and they belong to their own asset class — Mongo Fund — throughout the app. They are not real funds, and MongoTrader is not affiliated with or endorsed by any of the firms it tracks. They are practice instruments built from public data.

The six funds

The roster is deliberately short and focuses on concentrated, low-turnover books — the kind a 13F clone can approximate reasonably well:

• MBRK — Mongo Berkshire Fund, tracking Warren Buffett's Berkshire Hathaway.
• MPRS — Mongo Pershing Fund, tracking Bill Ackman's Pershing Square Capital Management.
• MTGR — Mongo Tiger Fund, tracking Chase Coleman's Tiger Global Management.
• MAPP — Mongo Appaloosa Fund, tracking David Tepper's Appaloosa LP.
• MTPC — Mongo Third Point Fund, tracking Dan Loeb's Third Point LLC.
• MDRK — Mongo Druckenmiller Fund, tracking Stanley Druckenmiller's Duquesne Family Office.

Multi-strategy "pod shop" firms are excluded on purpose. Their filings list thousands of hedged positions, and a public long book of that shape tells you almost nothing about how the firm actually performs. A concentrated manager with a handful of large, long-held positions is a different story: the 13F is a genuine, if delayed, picture of the portfolio.

How a fund is built from a filing

The pipeline runs the same way for every fund on the roster:

1. Pull the filing. MongoTrader fetches the latest 13F-HR for each firm directly from SEC EDGAR.
2. Resolve each holding to a ticker. Filings identify securities by CUSIP, so the first pass joins each CUSIP against MongoTrader's own symbol records — an exact, share-class-aware match. Anything left over goes through an issuer-name match against the SEC's company list, which proposes a ticker. That proposal only stands if the ticker exists in MongoTrader's catalog and, where the symbol's profile carries a CUSIP, it confirms the filing's CUSIP. Holdings that can't be resolved with confidence are recorded for review rather than guessed at.
3. Renormalize the weights. Weights are recomputed over the investable set — the holdings that resolved to a tradable ticker — so the fund is always fully expressed in symbols MongoTrader prices in real time.
4. Persist and publish. The composition is stored, each underlying symbol is activated so quotes and candles flow, and the fund's price begins tracking the weighted basket.

When a fund is first created it also receives about a year of synthesized daily history built from its constituents, so the chart is readable from day one rather than a single dot.

Monthly refresh and continuous pricing

Composition is refreshed monthly. Most months the latest filing is the one already in use and nothing changes. When a new filing lands, the fund rebalances to the new holdings — and the published price series stays continuous. The fund's NAV anchor is re-based at the moment of the rebalance, so the chart doesn't jump or reset when the composition changes; it simply starts moving with the new basket from that point forward. If you're holding a Mongo Fund through a rebalance, your position carries across the transition the same way it would through any other price move.

Trading a Mongo Fund

There is nothing special to learn. Search for a fund by ticker or name, open its detail page, and you'll find the same real-time price, chart and order ticket as any stock. Buy it in any of your portfolios with simulated money, hold it, add to it, or sell it. It marks to market alongside your other positions and counts toward your portfolio's performance like anything else you own. Because every constituent is a symbol MongoTrader already prices in real time, the fund's price is derived from live data rather than a stale end-of-day figure. If you want a refresher on reading the chart itself, our guide to how to read a stock chart applies to Mongo Funds exactly as it does to stocks.

A few ways people use them:

• Compare managers side by side. Hold equal amounts of MBRK, MPRS and MDRK for a month and watch how three very different approaches behave through the same market.
• Benchmark your own book. If your portfolio is trailing a fund built from public filings, that is useful information.
• Feel concentration. A fund with a few large positions moves differently from a broad index ETF. Holding one in a portfolio teaches more than reading about it.
• Practice patience. These are low-turnover books. Holding one through a quiet stretch is a good test of whether you can leave a position alone.

What a 13F clone can't tell you

Be honest about the limits. A 13F-HR is due within 45 days after the end of a quarter, so the holdings behind a Mongo Fund always lag the manager's real portfolio; by the time a filing is public, the firm may have added, trimmed or exited positions. The fund reflects the disclosed long book only, mapped onto the subset of holdings MongoTrader can price, with weights renormalized over that set. It is not the firm's fund, it does not carry the firm's fees or cash management, and its performance will differ from the real thing.

Treat a Mongo Fund as a well-built practice instrument for studying how a famous portfolio moves, not as a way to invest alongside anyone. Everything on MongoTrader is simulated money, and that is the point: you can hold a concentrated, high-conviction book for a quarter, live through its swings, and learn what that feels like without a dollar at risk. If you're weighing where to do that kind of practice, our comparison of the best stock market simulators covers what to look for.

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