3M Co.’s retreat from a $550 million office-products purchase amid regulatory pressure will let it focus on a bigger deal but forces Avery Dennison Corp. to put the unit it aims to sell back on the block. Investors may be concerned that Avery will struggle to get another offer at a price that comes close to 3M’s, said Ghansham Panjabi, an analyst at Robert W. Baird & Co. in New York.