S&P Global says outlook 'negative' on ADM

March 21 (Reuters) - S&P Global Ratings said on Thursday its outlook for global grain merchant Archer-Daniels-Midland Co was "negative", amid an ongoing investigation into the company's accounting practices.

ADM's CFO, Vikram Luthar, was placed on administrative leave in January as the company started a probe into the accounting practices at its Nutrition segment.

In January, S&P placed the company's ratings on "creditwatch negative" due to the investigation.

Last week, the company also confirmed some employees have received grand jury subpoenas from the Department of Justice, which is investigating its accounting practices. Reuters had reported that FBI agents delivered subpoenas in Illinois.

The ratings agency on Thursday affirmed ADM's 'A' issuer credit rating. (Reporting by Arunima Kumar in Bengaluru; Editing by Devika Syamnath)