Caterpillar (NYSE:CAT) shares fell over 2% in midday trading on Tuesday after the company announced sales of its retail machines slowed in the past months.In January, sales were up 47% then fell to 39% by mid-February even in Asia where sales fell to 20% in February.Caterpillar (NYSE:CAT) has potential upside of 17.3% based on a current price of $110.89 and an average consensus analyst price target of $130.11.