An analyst upgraded Hewlett-Packard Co. Wednesday, calling a recent pullback in the shares of the world’s largest technology company a “buying opportunity,” but said rival Dell Inc. has deeper problems than many on Wall Street think.

American Technology Research analyst Shaw Wu upgraded HP to “Buy” from “Neutral,” noting that the stock is down about 6 percent since the company posted its fiscal first-quarter results in February, compared with just a 2 percent decline in the Nasdaq and the S&P 500. Investors’ main concerns, he said, are over inventory and the lack of positive cash generation.