By Pamela Barbaglia, Saeed Azhar and Lananh Nguyen LONDON/NEW YORK (Reuters) – Goldman Sachs is planning a major reorganization to combine its biggest businesses into three divisions with its investment banking and trading businesses being merged into a single unit, two people familiar with the matter told Reuters. The plans are expected to be announced on Oct. 18 alongside Goldman’s third quarter earnings. Marcus, Goldman’s consumer banking business, will be absorbed into the wealth unit, the sources said, confirming an earlier Wall Street Journal report. A spokesperson for Goldman Sachs decl…