TheStreet

Stamps.com (STMP - Get Report) was tanking Thursday after the company said it expects full-year earnings of between $3.35 and $4.85 a share, well below its previous guidance and analysts' forecasts, on revenue of $510 million to $560 million.

The company previously said it expected full-year adjusted earnings of $5.15 to $6.15 a share.

Analysts had been calling for earnings of $5.43 a share for the year on revenue of nearly $555 million.

The stock fell 53.8% to $38.52 on Thursday. Earlier this year, the company said its key partnership with the U.S. Postal Service had ended.

Adjusted earnings in the first quarter for Stamps.com were $1.23 a share, beating forecasts of $1.11. Revenue of $136 million topped expectations of $127.2 million.