How to Analyze 13F Changes: New, Added, Trimmed and Exited Positions

A practical method for comparing two quarters of a fund's 13F: classifying new, added, reduced and exited positions, sizing them as a share of the portfolio, and avoiding the common traps.

A single 13F is a snapshot. The information is in the change between two snapshots. Here is a simple method.

Step 1: Line up two quarters

Take the latest 13F and the previous one for the same manager. Match positions by issuer and security class, not by name alone ("Alphabet Class A" and "Class C" are different lines).

Step 2: Classify each position

• New: in the latest filing, absent from the previous.
• Added: share count increased.
• Trimmed: share count decreased but not to zero.
• Exited: in the previous filing, absent now.
• Unchanged.

Use share count, not market value. Value changes with the stock price even if the fund did nothing.

Step 3: Size it

A change means little without scale. Compute:

• Weight: position value divided by the fund's total reported value.
• Change in weight: a new position at 0.3% is a toe in the water; a new 8% position is a conviction bet.
• Share of the company: compare the fund's shares with the company's shares outstanding. Large stakes may also trigger a 13D or 13G.

Step 4: Look at the whole portfolio

• Concentration: how much is in the top 10 positions.
• Turnover: how many positions changed. A fund that churns half its book each quarter is different from one that rarely moves.
• Sector tilt and whether it shifted.

Traps to avoid

1. The 45-day lag. By the time you see the filing, the fund may have already sold.
2. Long only. A fund "exiting" a stock may be switching to options or to a short that 13F cannot show.
3. Options lines. Puts and calls are reported separately from shares and can look like a big new position.
4. Amendments. A 13F-HR/A can correct or restate. Use the latest version.
5. Corporate actions. Splits, mergers and ticker changes can look like a trade.
6. Mandate. Index funds and quant funds change positions for mechanical reasons.

What to do with it

Use the changes to generate questions, not conclusions: why would this manager add here? Then check whether insiders at the company are acting too. Overlap is a better lead than any single filing.

Bourse imports 13F filings and shows how positions changed, next to Congress trades and insider filings.

Bourse provides financial data and editorial information, parts of which are generated by AI. This page is for general education only. It is not personalised investment advice or a recommendation to buy or sell any financial instrument. Make your own decisions.