Shares of Mosaic Co. MOS, -0.43% dropped nearly 5% in the extended session Monday after the producer of potash and phosphate fertilizers beat Wall Street expectations for its first quarter and said the outlook for the remainder of 2021 continued to be favorable. Mosaic said it earned $157 million, or 41 cents a share, in the quarter, versus a loss of $203 million, or 54 cents a share, in the year-ago quarter. Adjusted for one-time items, Mosaic said it earned 57 cents a share, versus a loss of 6 cents a share a year ago. Sales rose 28% to $2.3 billion, as the company “capitalized on stronger market conditions,” Mosaic said in a statement. Analysts polled by FactSet expected Mosaic to report adjusted earnings of 54 cents on sales of $2.26 billion. The outlook for the rest of the year remains favorable, and gross margins in the quarter were up almost 10 times mostly because of price increases, the company said. The stock ended the regular trading day down 0.4%. It has tripled in the past 12 months, compared with gains around 48% for the S&P 500 index.