Broadband software company Calix (NYSE:CALX) plunged in trading after it swung to a loss in the fourth quarter. The company reported a Q4 loss of $0.06 per share compared to earnings of $0.17 per share in the same period last year. Analysts were expecting the company to report earnings of $0.36 per share. On an adjusted basis, Calix reported earnings of $0.43 per share in the…