For investors used to the huge stock returns of the past six years, 2015 has been a disappointing year. The Dow Jones Industrials (^DJI -1.53%) have risen just 1.4% so far in 2015, and even with dividends, a 2% total return is far short of the typical rises the benchmark has posted in its rebound since 2009.

Still, the majority of stocks in the Dow are up on the year, with a few posting double-digit percentage gains. Yet three stocks in particular among the losers are holding back the Dow from further gains, with losses of more than 10% reflecting the current struggles of some of the biggest companies in the U.S.

Trouble in all corners
The three worst performers in the Dow so far this year come from three different sectors and face unique challenges. Intel (INTC -4.26%) ranks as the third-worst Dow stock in 2015, having lost 11%. After a year of surprisingly good results for the chipmaker thanks to a largely unexpected rebound in demand for PCs, Intel has fallen back amid the apparent completion of the upgrade cycle for the corporate desktop-computer market. Even as the stock's proponents look to positive results from the data center side of the business and promising efforts in the Internet of Things, Intel still gets the most attention for the revenue drops in its core client computing group, and the company will have to prove its transformation away from a reliance on PC-related sales in order to convince investors to look forward rather than backward with Intel.

Weighing in with a 12% drop is consumer products giant Procter & Gamble (PG -1.38%). P&G is a surprising entry on the list, especially for those who erroneously believe that stocks perceived as defensive plays always serve to prevent losses in choppy markets. The company's sales volume has dropped in four of its five major product lines, and that resulted in further slowing in organic growth to just 1% in its most recent quarter. Foreign-currency impacts have hurt profits substantially, and P&G gave investors a tiny 3% dividend increase in April, which was far less than it has done historically. Until the dollar stops soaring, Procter & Gamble isn't fulfilling its role of giving investors a relatively safe play in the stock market.

Finally, American Express (AXP -1.93%) tops the list of Dow losers with a 15% drop so far in 2015. The card company's multiple woes this year have drawn plenty of attention, in particular the high-profile loss of business from warehouse retail giant Costco Wholesale (COST -0.69%). The company's expenses have risen, suggesting that higher competition is eating into AmEx's business, particularly among high-income customers. Moreover, with economic conditions in several key international markets looking weaker than those in the U.S. right now, AmEx's historical global focus has held back its financial results lately.

Each of these three stocks has the potential to bounce back in the long run. For now, though, they're holding back the Dow Jones from posting more attractive returns in 2015, and their current trends suggest they are unlikely to start helping Dow investors anytime soon.