Higher for longer? Why the ASX 200 just turned negative

It was shaping up to be such a happy hump day for the S&P/ASX 200 Index (ASX: XJO). After closing at 9,164.6 points yesterday, the ASX 200 opened higher this morning, starting trade at above 9,180 points, and climbing to 9,220.6 points by mid-morning. That was just a whisker away from the index’s all-time high of 9.296.7 points.

Well-received earnings reports from ASX shares like Woolworths Group Ltd (ASX: WOW) and Perseus Mining Ltd (ASX: PRU), as well as the galloping BHP Group Ltd (ASX: BHP) share price, were all pulling their weight to lift the ASX 200 to that height. But alas, it wasn’t to last. Just before lunchtime, the index took a dramatic turn for the worse. It fell below the breakeven line just after midday, and is now firmly in negative territory, down 0.2% at the time of writing at just under 9,150 points.

So what has gone so wrong for the ASX 200 this Wednesday?

Well, it starts and stops with inflation. Specifically, the latest economic data out from the Australian Bureau of Statistics (ABS), covering the month of July.

As my Fool colleague Aaron went through earlier, the ABS revealed that inflation ran at 1% over July, giving the Australian economy an annual inflation rate of 3.5% for the preceding 12 months. Although that was down from 3.8% in June, it is still well above the Reserve Bank of Australia (RBA)’s target band of 203%.

Core inflation, which is the metric that the RBA prefers to use to measure price increases, was at 0.5% in July and 3.6% for the 12 months. That was higher than the 0.3% that most economists reportedly expected.

Why does higher inflation mean lower ASX 200 share prices?

Given that the ASX 200 began its downward turn almost immediately after these numbers were released today, it is clear that this is scaring investors. But why? Well, the obvious conclusion is that the market now expects inflation to remain higher for longer, and that means potentially higher interest rates sooner.

We all know that interest rates have severe impacts on the economy. Rate hikes are infamous for taking a larger chink of income from anyone with a mortgage. But they are also bad news for share prices. Higher rates increase the attractiveness of safe investments outside the share market. Think savings accounts, term deposits, and government bonds. If these investments, which are already offering investors safe yields of 5% or even higher, become even more attractive, many investors will pull money out of the share market and put it into these assets.

Further, investors often use ‘risk-free’ rates to put a value on ASX shares. This risk-free rate is usually a derivative of the cash rate. So it is this double-edged sword that cuts into share prices when interest rates rise. Investors know this, and given the higher-than-expected inflation number out today, are adjusting their expectations accordingly.

That’s probably why the ASX 200 took such a sharp turn for the worse during intra-day trading. Let’s see what happens tomorrow.