897,000 shares would have represented 1.5% of Monsanto stock. The actual largest shareholder of Monsanto, with a little over 6% ownership, is FMR, an investment fund controlled by the Johnson Family. Although not nearly as intriguing as rumor and innuendo, current ownership records are easily found at sites such as Yahoo Finance.
Your post that Gates didn’t own any stock was erroneous. He does, via his Foundation.