(Reuters) - Bunge missed Wall Street expectations for second-quarter profit on Wednesday, hurt by narrowing processing margins, sending the grain trader and processor's shares down nearly 6% before the opening bell.

The most-active soybean contract on the Chicago Board of Trade (CBOT) slumped nearly 7% in the second quarter, hurting margins for traders such as Bunge.

Bunge joins peer ADM which also reported weaker quarterly results on lower soy crush margins and waning demand for U.S. crops.

Net sales at Bunge's core Agribusiness segment, its largest by revenue and volume, fell to $9.66 billion in the April-June quarter from $10.88 billion a year earlier.

Strong results in Europe soy and softseed crush were more than offset by weakness in North and South America and Asia, the company said.

Earnings in Bunge's merchandising operations dropped, as higher grain volumes were more than offset by lower margins.

Bunge raised its full-year adjusted profit forecast to $9.25 per share, from $9.00 per share.

"Current market conditions have improved in some regions, but we continue to have limited visibility into the latter part of the year ... drivers of long-term demand remain strong," CEO Greg Heckman said.

Heckman also said the process for integration with Viterra is progressing well. The companies announced the deal to create one of the world's largest agriculture trading firms a year ago.

The merger is, however, facing regulatory headwinds in Europe and Canada. The EU is set to decide on the deal by Aug. 1.

Chesterfield, Missouri-based Bunge posted an adjusted profit of $1.73 per share for the quarter, compared with analysts' estimates of $1.80 per share, according to LSEG data.

(Reporting by Vallari Srivastava in Bengaluru; Editing by Maju Samuel)