What moves index markets
Learning objectives
Explain why interest rate expectations move equity indices, through the discount rate
Describe why the Nasdaq is more rate-sensitive than a broad index
Identify the index-specific factors that make each major benchmark behave differently
Understand the key drivers
Indices respond to the same macro forces as currencies, which is why lessons from our earlier Fundamental Analysis course are relevant once again.
What differs is the transmission mechanism, and understanding it explains why some indices move twice as far as others on identical news.
Let's take a look at the key influences on index prices.
Interest rate expectations
The dominant driver, and the mechanism is worth understanding rather than memorising.
A share is worth what its future earnings are worth today. Converting future money into present value requires a discount rate, and that discount rate is built on prevailing interest rates.
Raise rates and future earnings are worth less today, so share prices fall. Lower rates and they're worth more, so prices rise. This happens regardless of whether the companies' actual business has changed at all.
Which produces the relationship most beginners find confusing: good economic news can send an index down, because strong data raises the expected policy path, which raises the discount rate. The market isn't reacting to the economy. It's reacting to what the economy implies about rates.
Central banks 101 established that markets price an expected path of decisions rather than today's rate. Equity indices trade that path, continuously, and a change in it moves them faster than a change in earnings does.
Why duration explains the Nasdaq
Here's the refinement that does the real work.
Not every company's earnings sit at the same distance in the future. A mature utility earns steady profits now. A high-growth technology company is valued mostly on profits expected years out.
The further out the earnings, the more a change in the discount rate affects their present value. So companies valued on distant growth are far more rate-sensitive than companies valued on current cash generation.
This is why the Nasdaq 100 typically moves further than the S&P 500 on rate news, and why both move further than an index weighted toward energy and financials. It isn't that technology is inherently volatile. It's that its valuation depends more heavily on a number the central bank controls.
Two practical consequences. Choosing an index is partly choosing how much rate sensitivity you want. And in a rate-driven market, index selection matters more than usual, because the same news produces materially different moves.
Earnings
The other half of the valuation.
Individual company results matter less to an index than to a share, because the basket dilutes them. But earnings season matters, because hundreds of companies report within a few weeks and the aggregate picture updates.
Two things move the market more than the profit numbers themselves.
Guidance. What companies say about coming quarters shifts expectations for every quarter ahead, and expectations are what's priced.
The concentration effect. As What is an index: S&P 500, FTSE 100, Nasdaq explained, a handful of very large companies can dominate a market-cap-weighted index. When one of them reports, the index can move on a single set of results in a way the word "diversified" doesn't prepare you for.
Risk sentiment
Indices are the definitional risk asset. When capital moves toward safety it moves out of equities, and when confidence returns it moves back.
This channel can override the rate story entirely. A rate cut is normally supportive, but a rate cut delivered because the central bank is worried about a recession can send indices sharply lower, because the risk channel dominates the discount rate channel.
The same tension appeared in What drives precious metals between safe-haven demand and real rates. It's the same underlying structure: two channels, sometimes agreeing, sometimes not, and no reliable way to know in advance which will win.
Index-specific factors
The calendar
What to have marked, in order of typical impact:
- Central bank meetings for the relevant economy
- Inflation and employment data, which drive the expected rate path
- Earnings season, particularly the largest constituents
- Growth indicators, including manufacturing surveys
- The relevant currency, especially for non-US indices
Building a trading routine argued for checking this before every session, and index trading rewards it because so many of the largest moves are scheduled.
Key takeaways
Rate expectations dominate because they set the discount rate converting future earnings into present value. Strong economic data can therefore send an index down
Companies valued on distant future growth are more rate-sensitive, which is why the Nasdaq typically moves further than a broad index on the same news
Risk sentiment can override the rate channel entirely, which is why a rate cut delivered out of recession fear can send indices lower
For non-US indices the local currency is often a major driver, usually inversely, because the constituents earn abroad