1. Inflation metrics (CPI, PCE, WPI)

Why it matters: Inflation is like the thermostat central banks use to set interest rates. If inflation is cooling, the Fed, RBI, or ECB can cut rates — supportive for equities. If it re-accelerates, rate hikes or “higher for longer” policies follow — a headwind for stocks.

Early warning power: Inflation often shows up in consumer prices and producer prices before central bank policy shifts. A surprise uptick can sink markets in a single day.

How to watch it: Track headline CPI, but pay attention to core inflation (excluding food & energy) and sticky services inflation, which policymakers emphasize.

2. Labor market data (jobs reports, unemployment, wages)

• Why it matters: A strong labor market supports consumer spending, the engine of most economies. But if wages rise too fast, it can fuel inflation.
• Early warning power: Rising unemployment, slowing payroll growth, or fewer job openings often precede recessions and earnings downturns. Conversely, stabilizing or improving job data can signal recovery.
• How to watch it: In the U.S., nonfarm payrolls (monthly), jobless claims (weekly), and wage growth are closely watched. In India, CMIE employment surveys are useful.

3. Manufacturing & services PMIs (Purchasing Managers’ Index)

• Why it matters: PMIs are like real-time thermometers for business activity. They survey managers about new orders, hiring, and output.
• Early warning power: Because they’re forward-looking sentiment surveys, PMIs often dip below 50 before GDP data or earnings weaken — an early sign of slowdown. A bounce back above 50 can be an early sign of recovery.
• How to watch it: Look at both manufacturing and services PMIs; services matter even more in modern economies.

4. Corporate earnings & forward guidance

• Why it matters: Ultimately, stock prices follow profits. Quarterly earnings and, more importantly, management guidance reveal the health of demand, costs, and margins.
• Early warning power: Analysts often adjust earnings forecasts quickly after guidance changes. Sharp downward revisions in EPS estimates across many companies = red flag.
• How to watch it: Follow aggregate EPS revision trends for the S&P 500, Nifty 50, or sector indexes — not just single-company reports.

5. Yield curve & credit markets

• Why it matters: The bond market is often called “smarter” than equities because it reacts quickly to macro shifts.

Early warning power:

• Yield curve inversion (short-term rates higher than long-term rates) has historically preceded recessions.
• Credit spreads (difference between corporate bond yields and Treasuries) widening signals rising stress, especially in high-yield markets.
• How to watch it: Keep an eye on the 2-year vs. 10-year U.S. Treasury yield, and spreads on corporate bonds.

6. Consumer spending & confidence

• Why it matters: If consumers cut back, corporate revenues fall. Confidence surveys often dip before actual spending does.
• Early warning power: Sharp drops in consumer confidence or retail sales can signal weakening demand ahead of earnings season.
• How to watch it: University of Michigan Consumer Sentiment Index (U.S.), RBI Consumer Confidence Survey (India), or retail sales data.

7. Market internals & technical breadth

• Why it matters: Even before fundamentals show cracks, price action often whispers warnings.
• Early warning power: If indexes rise but fewer stocks participate (weak advance/decline lines, falling equal-weight indexes), the rally is fragile. Divergences between large-caps and small-caps are another clue.
• How to watch it:Track advance/decline ratios, % of stocks above 200-day moving average, and sector rotation.

8. Geopolitical & commodity signals

• Why it matters: Shocks in oil, gas, or shipping lanes feed into inflation and growth. Trade tensions, wars, or tariffs often ripple into equities.
• Early warning power: Spikes in oil prices, sudden trade barriers, or currency swings often foreshadow volatility.
• How to watch it: Brent crude prices, dollar index (DXY), and key geopolitical news.

9. Central bank communication (the “tone”)

• Why it matters: Policy is set by humans. The Fed’s dot plot, RBI minutes, or ECB speeches can move markets before any actual action.
• Early warning power: A shift in tone — even subtle — often precedes policy moves. “Data dependent” language turning into “prepared to act” is a tell.
• How to watch it: Read central bank statements side by side with previous ones; tiny word changes matter.

10. Retail flow & speculative activity

• Why it matters: Surges in retail flows, meme stock rallies, or heavy short-term options trading can inflate risk sentiment.
• Early warning power: Extreme spikes often precede corrections — they’re signs of froth.
• How to watch it: Track retail fund inflows, options activity (especially zero-day), and meme stock chatter on social media.

The human takeaway

No single data point is a crystal ball, but together they form a mosaic. A good investor’s early-warning system blends:

• Macro health checks (inflation, jobs, PMIs).
• Corporate health checks (earnings revisions, margins).
• Market stress checks (yield curve, credit spreads, breadth).
• Sentiment checks (consumer surveys, retail flows, frothy option activity).

It’s like flying a plane: no one gauge tells the whole story, but if three or four needles swing red at the same time, you know turbulence is ahead.