The S&P/ASX 200 Index (ASX: XJO) is up 0.4% today, but it's not getting any help from these two sinking ASX 200 shares.

Both companies are facing headwinds today after releasing earnings results and guidance.

Here's why they're under pressure.

ASX 200 share slides on full-year guidance

The Graincorp Ltd (ASX: GNC) share price is down 6.9% in late morning trade on Thursday, at $6.89.

Investors are bidding down the ASX 200 share after the agribusiness and processing company released its full-year FY 2025 earnings guidance.

Graincorp said it expected to report FY 2025 underlying earnings before interest, taxes, depreciation and amortisation (EBITDA) in the range of $270 million to $320 million. While that's up from EBITDA of $268 million reported in FY 2024, this excludes business transformation costs.

FY 2025 net profit after tax is forecast to be in the range of $60 million to $95 million, compared to NPAT of $77 million the prior year.

Graincorp CEO Robert Spurway said:

The winter crop harvest got off to an early start in Queensland and Northern NSW, and it was pleasing to see several of GrainCorp's sites in those regions achieve new grain receival records.

However, conditions were more challenging in southern regions, with the Victorian crop in particular down on recent seasons.

In a move that has yet to boost the ASX 200 share, Graincorp also announced its intention to conduct an on-market share buyback of up to $50 million.

"The share buyback reflects the strength of our balance sheet and delivers on our ongoing commitment to continue generating returns for shareholders through the cycle," Spurway said.

The Graincorp share price is down 16% since this time last year.

The company is holding its annual general meeting (AGM) today.

Also catching headwinds on Thursday…

The second ASX 200 share that's struggling today is Downer EDI Ltd (ASX: DOW).

Shares in the engineering, construction and maintenance services company were down 7.2% in earlier trade today at $5.15. After some likely bargain hunting, the Downer share price has recouped much of those losses to be down 0.9% at $5.50 a share.

This follows the release of Downer's half-year results (H1 FY 2025), covering the six months to 31 December.

Noting that the company's "turnaround is on track", Downer reported a 4.7%-year-on-year increase in statutory net profit after tax (NPAT) to $75.5 million.

In other core financial metrics, pro forma earnings before interest tax and amortisation (EBITA) came in at $204.4 million, up 37.1% from H1 FY 2024. Pro forma EBITA margin of 3.7% was up 1.1%.

On the negative side of the ledger for the ASX 200 share, pro forma revenue of $5.486 billion was down 5.2% year on year.

The board declared an interim dividend of 10.8 cents per share, 75% franked. That's up from the unfranked 6.0 cents per share interim payout last year.

Commenting on the half-year performance, Downer CEO Peter Tompkins said:

Downer's ability to generate strong cash conversion and ongoing EBITA margin improvement despite varied market conditions demonstrates the progress of our turnaround, and reinforces the resilience of our high quality, diversified mix of businesses.

The Downer share price is up 28% in a year, not including dividends.