Stamps.com Inc. /zigman2/quotes/202777086/composite STMP -2.62% shares cratered in the extended session Wednesday falling more than 38% after the company lowered its full-year guidance. The company reported first-quarter net income of $15.8 million, or 87 cents a share, compared with $47 million, or $2.54 a share, in the year-ago period. Adjusted for items such as stock-based compensation, earnings were $1.23 a share. Revenue rose to $136 million from $133.6 million in the year-ago period. Analysts surveyed by FactSet had estimated adjusted earnings of $1.11 a share on revenue of $127.2 million. For the second quarter, analysts model adjusted earnings of $1.20 a share on sales of $132.4 million. Stamps.com said it expects adjusted full-year earnings of $3.35 to $4.85 a share on sales of $510 million to $560 million. Stamps.com stock has dropped 65% in the past year, with the S&P 500 index /zigman2/quotes/210599714/realtime SPX -3.37% rising 8%. The company's stock dropped roughly 50% earlier this year after Stamps.com executives said its exclusive deal with the U.S. Postal Service would terminate.