Shares of MTC Technologies ( MTCT) were among the Nasdaq's losers Tuesday, falling 20% after the company posted second-quarter earnings that fell short of expectations and warned that third-quarter results would fall short of Wall Street forecasts.

The company, which provides system engineering, technical and management services to the federal government, earned $5.1 million, or 32 cents a share, on sales of $89.7 million. Analysts polled by Thomson First Call were expecting earnings of 34 cents a share on sales of $91.1 million. A year ago the company earned $4.2 million, or 27 cents a share, on sales of $62.7 million.

Looking ahead, MTC Technologies forecast third-quarter earnings of $5.05 million to $5.55 million, or 32 cents to 35 cents a share, on sales of $96.2 million to $101.2 million. Analysts had been expecting earnings of 41 cents a share on sales of $110.7 million. "The ongoing global war on terror and other factors are causing delays in the bidding/award process and are affecting funding availability and the availability of assets to be repaired or upgraded," the company said. Shares were trading down $7.68 to $30.05.

Pentair ( PNR) fell 9% after the company posted second-quarter earnings that matched forecasts but warned that third-quarter earnings would be well below analysts' expectations. The water-treatment products company earned $64.5 million, or 63 cents a share, on sales of $788.5 million. Analysts were expecting earnings of 63 cents a share on sales of $786.8 million. A year ago the company earned $42 million, or 42 cents a share, on sales of $530.4 million. Looking ahead, Pentair forecast third-quarter earnings of 43 cents to 47 cents a share. Analysts had been expecting earnings of 54 cents a share. Shares were trading down $4.09 to $40.39.

Shares of Rent-A-Center ( RCII) fell 6% after the rent-to-own operator posted second-quarter earnings that were a penny short of expectations and said that third-quarter earnings would be weaker than expected. The company reported pro forma earnings of $39.6 million, or 52 cents a share, on sales of $580.6 million. Analysts were expecting earnings of 53 cents a share on sales of $575.1 million. A year ago the company earned $51.2 million, or 62 cents a share, on sales of $573 million. The company said the year-over-year decline in earnings was attributed to a decrease in same-store sales and higher operating expenses.

Looking ahead, Rent-A-Center said that its business environment remains challenged. "We currently have fewer agreements on rent relative to our prior expectations due to weaker than expected demand in June and to date in the month of July," it said. The company forecast third-quarter earnings of 38 cents to 42 cents a share on sales of $572 million to $580 million. Analysts had been expecting earnings of 51 cents a share on sales of $571.7 million. Shares were trading down $1.47 to $21.86.

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