The Insurance Australia Group Ltd (ASX: IAG) share price dropped 3.52% to an intraday low of $8.78 on Thursday.
IAG stock has since regained some minor ground but is still one of the five biggest fallers of the S&P/ASX 200 Index (ASX: XJO) today.
At the time of writing, the IAG share price is $8.82, down 3.13%.
Meanwhile, the ASX 200 has cracked another record high and surpassed 9,000 points for the first time ever.
The ASX 200 lifted 1.07% to hit a new peak of 9,013.3 points in earlier trading.
So, what's going on with IAG shares?
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Why is the IAG share price among the market's weakest today?
It's ex-dividend day. Simple as that.
It's typical for a company's share price to fall on ex-dividend day because the stock is no longer trading with the next dividend attached.
That means it's inherently less valuable.
As the August earnings season continues, IAG is among several ASX shares going ex-dividend this week.
IAG shares will pay a final dividend of 19 cents per share with 40% franking on 18 September.
This is 11.8% higher than the FY24 final dividend.
The full-year FY25 dividend totalled 31 cents per share, up 14.8% from FY24.
The ex-dividend day presents a handy opportunity for investors who want to buy an ASX stock.
The almost inevitable share price drop on ex-dividend day allows investors to pick up their targeted stock at a lower price.
Based on today's IAG share price, the 12-month trailing dividend is currently 3.5%.
That's only a tad higher than the average dividend yield that the ASX 200 is delivering these days.
The ASX 200 has a long history of producing a 4% to 4.5% annual dividend yield — among the highest in the world.
But as we've reported, this has changed.
Betashares says the trailing cash dividend yield of the ASX 200 is now tracking at 3.34% per year.
This is largely because the ASX 200 mining and bank shares are paying lower dividend yields than usual at the moment.
Check out our recent story on the forecast dividends from the major ASX 200 banks and mining shares for 2026.
A recap on IAG's FY25 results
In its full-year FY25 results, IAG reported a 51.3% year-over-year rise in net profit after tax (NPAT) to $1.36 billion.
The company's insurance profit was $1.74 billion, up 21.2% on FY24.
The gross written premium (GWP) lifted 4.3% year over year to $17.11 billion. The net earned premium rose 8% to $9.98 billion.
IAG provided FY26 guidance of "low-to-mid single digit" GWP growth.
The insurer forecasts a reported insurance profit of between $1.45 billion and $1.65 billion next year.
That would equate to a reported insurance margin of 14% to 16%.
IAG said its forecasts do not include the impact of its pending purchases of RACQ Insurance (RACQI) and RAC Insurance (RACI).
IAG expects the RACQI acquisition to be completed on 1 September.
