Vectren ( VVC), an energy holding company, said its second-quarter earnings plunged from a year ago. The Evansville, Ind., company earned $4.3 million, or 6 cents a share, in the quarter, compared with $13.4 million, or 18 cents a share, a year ago. Excluding items, the company earned 12 cents a share. Analysts polled by Thomson First Call were expecting earnings of 16 cents a share in the most recent quarter. Second-quarter revenue fell 2.7% to $317.5 million. The company also lowered its full-year earnings guidance to a range of $1.55 to $1.70 a share from $1.65 to $1.80 a share. Analysts were expecting full-year earnings of $1.74 a share.