🐋 13F Holdings Delta Tracker — Quarterly Position Changes for Berkshire, Tiger, Bridgewater & Every Hedge Fund

Stop reading raw 13F filings. Start reading the deltas. This actor pulls each fund's two most recent SEC Form 13F-HR filings, diffs the positions by CUSIP, and returns one clean row per new position, increased stake, reduced stake, or full exit — the actionable hedge-fund signal that subscriptions like WhaleWisdom Premium charge $999/year for.

When Warren Buffett's Berkshire Hathaway buys a brand-new $1.2 billion stake in Sirius XM, the raw 13F shows you 47 lines of identical Apple, Bank of America, and Coca-Cola holdings — same as last quarter, same as the quarter before. The signal is buried in those 47 lines as a single new row. The same is true for every whale: Tiger Global, Bridgewater, Renaissance, Pershing Square, Third Point, Greenlight, Appaloosa, Citadel, Point72, Coatue, Lone Pine, Viking. Each quarter their information tables run hundreds of pages — but the delta is what hedge funds, family offices, and quant shops actually pay to see.

This actor does that diff for you. Point it at a single fund or a list of 50 whales, and it returns:

• NEW positions (zero last quarter → non-zero this quarter — the freshest conviction trade)
• INCREASED stakes (existing position grew in shares)
• DECREASED stakes (existing position shrunk)
• EXITED positions (position went to zero — fund lost conviction or rotated)

Plus a is_top10_new boolean — true when a stock vaulted into the fund's top 10 holdings this quarter (the strongest single-delta signal in 13F land).

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What 13F Is (And Why The Deltas Matter)

Under SEC Rule 13F, every institutional investment manager with $100 million or more in qualifying US-listed equities must file Form 13F-HR within 45 days of each calendar quarter end. The filing discloses every long equity position the manager held on the last day of the quarter — issuer name, CUSIP, share count, USD value, voting authority.

The raw 13F is public, free, and useless on its own at scale. A typical mega-fund (Renaissance, Citadel, Two Sigma) files 2,000–8,000 positions per quarter. Berkshire is unusual in its concentration — most quants file what looks like a paint-by-numbers replica of the Russell 3000 with a tilt.

The signal is in the diff. When a fund:

• Initiates a brand new top-20 position → high-conviction fresh idea
• Doubles an existing stake → conviction reinforcement
• Fully exits a name → loss of conviction
• Vaults a new name into the top 10 → multi-hundred-million capital commitment

These are the moves the Sohn Conference talks, the Berkshire fan-club newsletters, and the Robinhood trades-of-the-day react to within 24 hours of every 45-day filing window.

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Output Schema

Each dataset item is one stock-level position delta for one fund-quarter:

Field	Type	Example
filer_name	str	BERKSHIRE HATHAWAY INC
filer_cik	str	0001067983
period_of_report	str	2025-12-31
prior_period_of_report	str	2025-09-30
symbol	str | null	AAPL (best-effort CUSIP→ticker lookup)
company_name	str	APPLE INC
title_of_class	str	COM
cusip	str	037833100
delta_type	enum	NEW / INCREASED / DECREASED / EXITED
shares_current	int	300000000
shares_prior	int	400000000
shares_change	int	-100000000 (signed)
pct_change	float | null	-25.0 (null for NEW — undefined %)
value_usd_current	int	72000000000
value_usd_prior	int	92000000000
value_usd_change	int	-20000000000
pct_of_portfolio_current	float	21.5
is_new_position	bool	false
is_full_exit	bool	false
is_top10_new	bool	false (entered top 10 this quarter)
filing_url	str	https://www.sec.gov/Archives/edgar/data/.../infotable.xml
data_source	str	sec.gov EDGAR 13F-HR

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Input Filters

Filter	Type	Description
fund_names	array	Case-insensitive substring match against EDGAR filer names. Defaults to ["Berkshire Hathaway", "Tiger Global"].
fund_ciks	array	Exact 10-digit CIK lookups for ambiguous filer names.
delta_types	array	Subset of NEW/INCREASED/DECREASED/EXITED. Defaults to ["NEW","INCREASED"].
min_value_usd	int	Skip deltas under this USD position size.
min_shares_change_pct	int	Skip INCREASED/DECREASED where abs(% change) < this. NEW/EXITED always pass.
limit	int (1–2000)	Max delta records to return.
include_top10_flag	bool	Compute the is_top10_new boolean (true = entered top 10 this quarter).

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Use Cases

1. Hedge Funds & Quant Shops — Clone Strategies

Build a long-only basket that buys every NEW position the top 20 whales initiate above $50M. Backtests of "whale-clone" portfolios have shown 2–4% annualized alpha vs the S&P 500 over the last 15 years (with a 45-day lag from the filing date — the strategy isn't dead, but it's not free money either).

2. Family Offices & RIAs — "What Did Buffett Just Buy?"

Run the actor weekly with fund_names: ["Berkshire Hathaway"] and email any NEW positions or top-10 entries to your investment committee. The Sohn-conference idea-of-the-day, but automated.

3. Activists & M&A Bankers — Concentration Detection

Watch for INCREASED stakes by known activists (Icahn, Ackman, Loeb, Trian, Engaged Capital, JANA, Starboard) — these often precede public 13D/G campaigns by weeks.

4. Single-Stock Conviction Tracking

Filter by delta_types: ["EXITED"] to see which whales are quietly selling a name you own. EXITED-by-3-whales-in-one-quarter is a strong "they know something" signal worth investigating.

5. Retail Smart-Money Followers

The TikTok / r/wallstreetbets "Buffett bought X" hype cycle peaks 2–4 hours after each filing window. Run this actor at 4:01pm ET on the 45-day-from-quarter-end deadline date and you're ahead of 99% of retail.

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Comparison vs Bloomberg / WhaleWisdom Premium / HedgeFollow Pro / Backtrader / FactSet

Capability	This Actor	Bloomberg Terminal	WhaleWisdom Premium	HedgeFollow Pro	Backtrader / Custom	FactSet
Quarterly position deltas (NEW/INCR/DECR/EXIT)	✅	✅	✅	✅	⚠ DIY	✅
Top-10 entry flag	✅	⚠ manual	✅	⚠ partial	❌	✅
Full SEC filing URL per row	✅	⚠ separate	❌	⚠ link only	⚠ DIY	⚠ separate
CUSIP-level diff (not just ticker)	✅	✅	⚠ ticker-only	⚠ ticker-only	⚠ DIY	✅
% portfolio weight current	✅	✅	✅	✅	⚠ DIY	✅
50-whale curated default list	✅	❌	✅	✅	❌	❌
API / programmatic access	✅	✅ ($24K/yr)	✅ ($999/yr)	✅ ($249/yr)	⚠ self-host	✅ ($30K/yr)
Anti-bot risk	None (direct SEC)	n/a	High (aggregator)	High (aggregator)	n/a	n/a
Data source	SEC EDGAR official	proprietary	aggregator	aggregator	SEC EDGAR	proprietary
Pay-per-result pricing	✅ $0.25/delta	❌ flat	❌ flat	❌ flat	❌ infra cost	❌ flat
Annual cost @ 500 deltas/yr	$125	$24,000+	$999	$249	$0 + dev time	$30,000+

Bottom line: if you want the actionable delta — not the raw 47-row filing — at the price of a couple of coffees per quarter, this is the cheapest path. WhaleWisdom and HedgeFollow do this too but their aggregator-based pipelines are anti-bot-fragile; we hit SEC EDGAR directly (the source of truth) so the data is unblockable.

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Example Output

{
  "filer_name": "BERKSHIRE HATHAWAY INC",
  "filer_cik": "0001067983",
  "period_of_report": "2025-12-31",
  "prior_period_of_report": "2025-09-30",
  "symbol": "SIRI",
  "company_name": "SIRIUS XM HLDGS INC",
  "title_of_class": "COM",
  "cusip": "82968B103",
  "delta_type": "NEW",
  "shares_current": 132311566,
  "shares_prior": 0,
  "shares_change": 132311566,
  "pct_change": null,
  "value_usd_current": 1180000000,
  "value_usd_prior": 0,
  "value_usd_change": 1180000000,
  "pct_of_portfolio_current": 0.41,
  "is_new_position": true,
  "is_full_exit": false,
  "is_top10_new": false,
  "filing_url": "https://www.sec.gov/Archives/edgar/data/1067983/000119312526054580/50240.xml",
  "data_source": "sec.gov EDGAR 13F-HR (official, free)"
}

---

Quickstart

Apify Console

1. Click Start on the actor page.
2. Set fund_names: ["Berkshire Hathaway", "Tiger Global"], delta_types: ["NEW","INCREASED"], limit: 5.
3. Hit Run. Results appear in ~30 seconds.

cURL

curl -X POST "https://api.apify.com/v2/acts/nexgendata~13f-holdings-delta-tracker/run-sync-get-dataset-items?token=YOUR_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"fund_names": ["Berkshire Hathaway"], "delta_types": ["NEW","INCREASED"], "limit": 20}'

Python SDK

from apify_client import ApifyClient

client = ApifyClient("YOUR_TOKEN")
run = client.actor("nexgendata/13f-holdings-delta-tracker").call(run_input={
    "fund_names": ["Berkshire Hathaway", "Tiger Global", "Pershing Square"],
    "delta_types": ["NEW", "INCREASED"],
    "min_value_usd": 10000000,
    "limit": 100,
})
for item in client.dataset(run["defaultDatasetId"]).iterate_items():
    print(f"{item['filer_name']}: {item['delta_type']} "
          f"{item['company_name']} (${item['value_usd_current']:,})")

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Pricing

$0.25 per delta record returned, plus $0.01 per actor start.

• Smoke test (5 deltas): $1.26
• Weekly whale-monitor (50 deltas): $12.51/week, ~$650/year
• Quarterly mega-pull (500 deltas across 50 whales): $125.01/quarter, ~$500/year

Compare to: WhaleWisdom Premium ($999/year flat), HedgeFollow Pro ($249/year, limited), Bloomberg Terminal ($24K+/year). The premium $0.25/record reflects that each delta record is high-value hedge-fund signal — not just raw filing data — and that the actor pre-computes the top-10-entry flag, % portfolio weight, and signed share change so you don't have to.

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How It Works

Primary data source: SEC EDGAR (data.sec.gov/submissions/ + www.sec.gov/Archives/edgar/data/) — official, free, JSON+XML, no anti-bot.

Pipeline per fund:

1. Resolve fund_name → CIK via curated 50-fund whale list, or accept exact CIKs.
2. Fetch the fund's EDGAR submissions JSON.
3. Identify the two most recent 13F-HR accession numbers.
4. Fetch each filing's information-table XML (the structured holdings list).
5. Parse + aggregate by CUSIP (a fund can hold multiple lots of the same CUSIP under different voting/discretion classifications).
6. Auto-normalize value fields (post-2022 files report USD; pre-2022 reported thousands).
7. Diff the two CUSIP sets → emit one record per non-zero delta.
8. Rank: NEW first, then by absolute USD change desc.

No aggregator dependency. Unlike WhaleWisdom or HedgeFollow, we don't rely on a third-party that can ban our IP or break their HTML. SEC EDGAR is the source of truth — it cannot rate-limit us beyond ~10 req/sec, which we already throttle below.

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FAQ

Q: Why only US-listed equities? A: Form 13F is a US-only filing. Non-US institutional disclosures (UK FCA, ESMA, Japan TOSHO) follow different rules with different fields. For non-US: see the Schedule 13D/G Activist Tracker for cross-border activist stakes.

Q: Are short positions or derivatives included? A: No. 13F is long-equity-only by SEC design. Short positions are not disclosed publicly; option positions (puts/calls) are filtered out by this actor because their delta signal is too noisy to be useful (most are hedges, not directional bets).

Q: How do you handle 13F amendments (13F-HR/A)? A: We pull only the original 13F-HR filings (the as-of-quarter-end snapshot). Amendments are rare and usually correct minor CUSIP typos. If a fund frequently amends, consider running with their CIK and dialing min_value_usd higher.

Q: What's the lag between quarter end and filing? A: Up to 45 days. Most mega-funds file on day 44 (the deadline). Berkshire is famously last (typically files at 4:01pm ET on day 45). The actor will surface deltas as soon as both quarter filings exist in EDGAR.

Q: Can I monitor a fund whose CIK I don't know? A: Yes — pass fund_names: ["Some Manager"]. We match substring against the curated whale list. If your fund isn't in the list, supply the CIK directly via fund_ciks: ["XXXXXXXXXX"]. Look up CIKs at https://www.sec.gov/cgi-bin/browse-edgar.

Q: How current is the curated whale list? A: Updated quarterly with the 50 highest-AUM US-equity institutional managers tracked by the major hedge-fund-follower communities (Sohn, Tiger Cubs, activist crowd, value crowd, quant crowd).

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Related Actors — Build A Full Smart-Money Stack

Actor	What It Does
SEC Form 13F Holdings Tracker	Raw quarterly 13F filings (all positions, not just deltas) — the upstream cousin to this actor.
SEC Form 4 Insider Trading Tracker	CEO/CFO/Director buys & sells with cluster-buy detection (2-day filing window).
SEC Schedule 13D/G Activist Tracker	5%+ ownership stakes by activists (Icahn, Ackman, Loeb, JANA).
Short Interest Tracker	Bi-monthly short-interest data — pair with EXITED deltas for "smart money + shorts" conviction screens.
Startup Funding Tracker	Private-market raises — see when fund whales are deploying capital into pre-IPO names.
Finance MCP Server	LLM-ready finance data — give Claude / GPT access to whale flows, fundamentals, charts.

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Disclaimer

This actor returns public SEC Form 13F-HR filing data sourced directly from SEC EDGAR. All positions are filed by the institutional managers themselves under SEC regulation; we add the quarter-over-quarter diff computation, the top-10-entry flag, and the % portfolio weight. This is not investment advice. 13F filings are reported with up to a 45-day lag — the fund may have already changed its position before the deltas reach you. Past performance does not predict future results.

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