The stock market performed well last week, as the Dow Jones Industrials (^DJI -0.11%) picked up 115 points and recovered from substantial losses early in the week. Yet even though the general attitude on Wall Street was a positive one, not every component in the Dow Jones Industrials managed to post gains. In fact, seven Dow components lost ground last week, and AT&T (T 1.88%), Caterpillar (CAT 0.07%), and Wal-Mart (WMT 1.32%) were the worst performers among them.

Source: AT&T.

AT&T fell almost 4% last week as investors reacted to the Dow telecom's decision to buy satellite video specialist DirecTV. With a wave of consolidation going on in the U.S. telecom and content-delivery space right now, AT&T was clearly nervous about having gotten shut out in its past attempts to grow through acquisition. As cable giants combine, the acquisition could help AT&T offer a broader package of entertainment services. Yet shareholders don't seem to be happy on either side of the transaction, as DirecTV shareholders are trying to hold out for a higher price while AT&T investors worry about the variable amount of stock that they'd be required to give DirecTV shareholders under the deal. With limited options, though, the deal appears to be the best that AT&T could put together in an industry where competition and regulation combine to make mergers difficult at best.

Source: Caterpillar.

Caterpillar declined nearly 2% as the heavy-equipment maker reported another ugly set of sales figures for the past three months. Overall, machine sales fell by 13% worldwide, and the mining-equipment segment has hit Caterpillar especially hard given the huge plunge in metals prices and the consequent decision from many mining companies to defer or reduce capital expenditures on equipment and other long-term needs. Yet North America is a bastion of strength for Caterpillar, and the construction industry looks like it's improving in most areas of the world. If Caterpillar can survive until the next cyclical upturn in the global economy, it might find that it's made it through the worst of its problems and could enjoy some growth.

Source: Wal-Mart.

Wal-Mart's almost 2% drop stemmed from ongoing fallout after its disappointing earnings report last week. With fellow retailers having struggles of their own, it's clear that some of the problems that Wal-Mart is facing aren't unique to the retail giant. Yet Wal-Mart's target customer base faces issues that have hurt shoppers' ability to bolster Wal-Mart's growth. In response, Wal-Mart hopes to open smaller stores in more convenient locations to cater to the different needs that customers have at various times, but it'll take time for Wal-Mart to prove that its new approach could reverse the trend of falling same-store sales and other troubling trends in the retailer's financials.