sector-rotation-signal
You hand over a rotation window (default 30 days) and get back the
current 20-day RS rank per sector, the rank change over the window,
and a rotation classification (rotating in, stable, rotating out).
Bundled with a plain-English theme read.
Rank change is the leading signal. The tape already prices absolute
strength; leadership rotation is what tells you the composition of
strength is shifting.
When to invoke
- The user asks "what sectors are rotating", "is the market rotating",
"growth vs value right now"
- market-regime shows the same label two days in a row but you want
to know if the underlying composition is changing
- Portfolio-review workflow, after market-regime — regime says WHAT,
rotation-signal says WHERE-IT'S-MOVING
- A single-name research question wants sector context: "is my
Tech position bucking the sector rotation"
What you need
MASSIVE_API_KEY (Stocks Starter). One daily-aggs call per SPDR
sector ETF + SPY (12 calls total).
What you get back
Layer 1 JSON matching output-schema.json.
Per-sector: current 20-day RS rank, rank in the reference date,
rank_delta, 20-day RS in basis points, secondary RS window, rotation
classification, category tags.
Layer 2 rendered table sorted by current rank. Rotation column
uses arrows (↑, ↑↑, ↓, ↓↓, stable) so the visual read is
immediate. Theme line above the table. See
references/rendering.md.
How it works
- Fetch SPY + 11 sector ETFs over
lookback_days (default 252)
using the same helpers as market-regime.
- Compute RS ranks on two reference days:
now (latest trading
day) and then (latest trading day <= today - rotation_window).
RS is sector_return - spy_return over the primary RS window
(default 20 days), reported in basis points.
- Compute rank_delta = rank_then - rank_now (positive means the
sector moved UP the leadership order, i.e. rank number went DOWN).
- Classify each sector: rotating_in_strong (delta >= +3),
rotating_in (>= +2), stable (|delta| <= 1), rotating_out (<= -2),
rotating_out_strong (<= -3).
- Generate theme read based on which category buckets (growth,
defensive, value-cyclical, rate-sensitive) are receiving inflows
vs outflows.
Category tags
- growth: XLK, XLY, XLC
- defensive: XLP, XLU, XLV
- value_cyclical: XLE, XLI, XLB, XLF
- rate_sensitive: XLRE, XLU, XLF (overlap intentional)
Endpoints used
GET /v2/aggs/ticker/{ticker}/range/1/day/{from}/{to} for SPY +
11 sector ETFs
Doesn't handle (yet)
- A 1-position rank move is inside the noise floor. Deliberately
classified as
stable. Users who want fine-grain rotation should
use a longer rotation window.
- SPDR sector ETFs are a proxy for the full sector universe.
Real-world sector performance can diverge from the ETF (especially
in Energy, where XLE is oil-major heavy).
- RS is past-return, not predictive. Rotation captures a shift
in what's working, not what will work next.
- Rotation reads are heuristic. Real regime classification
belongs in a dedicated macro tool; this is a change-detection
surface, not a regime call.
1---2name: sector-rotation-signal3description: Change-detection layer on top of market-regime. market-regime reports current sector leadership as a snapshot; this skill tracks how the leadership order has changed over a rotation window (default 30 days) and flags sectors moving up or down the ranks. Categorizes moves into growth / value-cyclical / defensive / rate-sensitive buckets and generates a plain-English theme read. Use when the daily regime hasn't moved but the composition of leadership is shifting — the actual tradeable signal.4---56# sector-rotation-signal78You hand over a rotation window (default 30 days) and get back the9current 20-day RS rank per sector, the rank change over the window,10and a rotation classification (rotating in, stable, rotating out).11Bundled with a plain-English theme read.1213Rank change is the leading signal. The tape already prices absolute14strength; leadership rotation is what tells you the composition of15strength is shifting.1617## When to invoke1819- The user asks "what sectors are rotating", "is the market rotating",20 "growth vs value right now"21- market-regime shows the same label two days in a row but you want22 to know if the underlying composition is changing23- Portfolio-review workflow, after market-regime — regime says WHAT,24 rotation-signal says WHERE-IT'S-MOVING25- A single-name research question wants sector context: "is my26 Tech position bucking the sector rotation"2728## What you need2930- `MASSIVE_API_KEY` (Stocks Starter). One daily-aggs call per SPDR31 sector ETF + SPY (12 calls total).3233## What you get back3435**Layer 1 JSON** matching [`output-schema.json`](./output-schema.json).36Per-sector: current 20-day RS rank, rank in the reference date,37rank_delta, 20-day RS in basis points, secondary RS window, rotation38classification, category tags.3940**Layer 2 rendered table** sorted by current rank. Rotation column41uses arrows (`↑`, `↑↑`, `↓`, `↓↓`, `stable`) so the visual read is42immediate. Theme line above the table. See43[`references/rendering.md`](./references/rendering.md).4445## How it works46471. **Fetch SPY + 11 sector ETFs** over `lookback_days` (default 252)48 using the same helpers as market-regime.492. **Compute RS ranks on two reference days**: `now` (latest trading50 day) and `then` (latest trading day <= today - rotation_window).51 RS is `sector_return - spy_return` over the primary RS window52 (default 20 days), reported in basis points.533. **Compute rank_delta** = rank_then - rank_now (positive means the54 sector moved UP the leadership order, i.e. rank number went DOWN).554. **Classify each sector**: rotating_in_strong (delta >= +3),56 rotating_in (>= +2), stable (|delta| <= 1), rotating_out (<= -2),57 rotating_out_strong (<= -3).585. **Generate theme read** based on which category buckets (growth,59 defensive, value-cyclical, rate-sensitive) are receiving inflows60 vs outflows.6162## Category tags6364- **growth**: XLK, XLY, XLC65- **defensive**: XLP, XLU, XLV66- **value_cyclical**: XLE, XLI, XLB, XLF67- **rate_sensitive**: XLRE, XLU, XLF (overlap intentional)6869## Endpoints used7071- `GET /v2/aggs/ticker/{ticker}/range/1/day/{from}/{to}` for SPY +72 11 sector ETFs7374## Doesn't handle (yet)7576- **A 1-position rank move is inside the noise floor.** Deliberately77 classified as `stable`. Users who want fine-grain rotation should78 use a longer rotation window.79- **SPDR sector ETFs are a proxy for the full sector universe.**80 Real-world sector performance can diverge from the ETF (especially81 in Energy, where XLE is oil-major heavy).82- **RS is past-return, not predictive.** Rotation captures a shift83 in what's working, not what will work next.84- **Rotation reads are heuristic.** Real regime classification85 belongs in a dedicated macro tool; this is a change-detection86 surface, not a regime call.
rgourley