The Kroger Co. is forecasting a rosier year after the company's customer-loyalty programs helped boost net income in the first quarter.

The nation's largest traditional grocery store chain says it earned $439.4 million, or 78 cents per share, for the three months ended May 19. That compares with $432.3 million, or 70 cents a share, a year ago. The higher per-share figure in the latest quarter was the result of a reduced number of outstanding shares.

Analysts on average expected a profit of 72 cents per share, according to FactSet.

The Cincinnati-based company, which operates Ralphs, Food 4 Less and other grocery stores, also says it authorized a $1 billion share buyback.

For the quarter, Kroger said revenue at stores open at least a year rose 4.2 percent, marking the 34th straight quarter of growth. The figure is a key performance metric because it strips out the effect of newly opened and closed stores.

Total revenue for the quarter was $29.06 billion, up from $27.46 billion but shy of Wall Street expectations of $29.16 billion.

Based on the strong first quarter, the company lifted its outlook for the year to $2.33 to $2.40 per share, up from the previous $2.28 to $2.38 per share. Analysts expected $2.32 per share.

Shares of Kroger were up $1.01, or almost 5 percent, at $22.30, in pre-market trading.