NEW YORK — Stocks stormed higher Tuesday after promising signals about the profitability of U.S. companies and a strong debt auction by Spain. The Dow Jones industrial average rose for the fourth day in five and posted its biggest gain in a month.

In the U.S., first-quarter results have begun to pour in from companies, and traders have been impressed so far.

Also, European stocks had their best day in four months after Spain, the latest flashpoint in the European debt crisis, attracted strong investor interest at an auction of two-year debt.

The Dow Jones industrial average closed up 194.13, or 1.5 percent, at 13,115.54.

The S&P 500 gained 21.21, or 1.6 percent, to 1,390.78.

The Nasdaq composite index soared 54.42, or 1.8 percent, to 3,042.82.

The State Ports Authority is doubling the cash incentive it offers truckers who upgrade their pre-1994 rigs to newer models that don’t pollute as much.

Eligible drivers now can qualify for a $10,000 subsidy, plus the scrap value of their existing vehicles, the SPA said. The money must be applied toward the a truck made in 2004 or later.

The SPA said an office is being set up at its Wando Welch Terminal in Mount Pleasant to promote the initiative. It will be open each Tuesday from 9 a.m. to noon starting April 24.

COLUMBIA — Sandwich spread maker Duke Sandwich Productions is investing $5 million in a new plant in Anderson County.

Secretary of Commerce Bobby Hitt said Tuesday that the company, which traces its history in South Carolina back nearly 100 years, expects to add 45 jobs at the Powdersville factory.

Duke Sandwich said it will hire in September, and have the plant open by the end of that month.

NEW YORK — Coca-Cola is continuing to expand its reach worldwide and turning to a variety of smaller drink sizes to boost profits and keep rising commodity costs in check.

The world’s biggest soda maker reported Tuesday a better-than-expected profit $2.05 billion for its first quarter. Total revenue was $11.14 billion, up 6 percent.

Although the volume growth came from all regions, Coca-Cola said increases were far greater in emerging markets.

JACKSONVILLE, Fla. — Higher rates helped freight railroad CSX boost profits by 14 percent despite a drop in coal shipments. CSX said Tuesday it earned $449 million.

Revenue rose 6 percent to $2.97 billion; analysts expected $2.91 billion.

CSX is the first large railroad to report first-quarter results. Railroads are a snapshot of the economy because so many consumer goods, from autos to yard fertilizer, move by train.

Staff and wire reports