NEW YORK — In the worst one-day stock market decline since the heart of the 2008-09 recession, grain-based foods shares lost ground but not nearly as much as the overall market. The Grain-based Foods Share Index, as calculated by Milling & Baking News, fell 344.09 points, or 2.9%, closing Aug. 4 at 11378.13. The decline compared with drops of 4.3% for the Dow Jones average of industrial shares; 4.8% for the S.&P.500; and 5.1% for Nasdaq. And while the broader indexes ended Aug. 4 down for the year to date, grain-based shares were up almost exactly 100 points, or 1%, from 11278.36. Still, the Grain-based Foods Share Index was not without serious casualties for the day, most notably Ralcorp Holdings, which closed at $75.50, down 10%. Corn Products Holdings closed at $45.56, also down 10%. While trading in each of the 21 U.S. companies in the index ended with a decline for Aug. 4, a couple companies escaped nearly relatively unscathed, beginning with Kraft Foods Inc., at $33.78, down 52c, or 1.5%. Before the market opened, Kraft announced plans to split up into two separate publicly traded companies.