Leasing segment revenues were $6.5 million for the first quarter of 2013, an increase of $5.1 million over the $1.4 million for the same period in 2012. The primary reason for the increase in revenue was an increase in the number of railcars on lease. We had approximately 3,120 railcars in the Company's lease fleet at the end of the first quarter of 2013, compared to approximately 950 railcars at the end of the same period in 2012.
Consolidated earnings from operations for the first quarter of 2013 were $31.2 million, an increase of 31% over the $23.8 million for the same period in 2012. Operating margins were 16% for the first quarter of 2013 compared to 13% for the comparable quarter of 2012. The increase in consolidated earnings was primarily due to an increase in the Company's manufacturing earnings from operations, partially offset by an increase in the Company's selling, general and administrative expenses driven by an increase in our share-based compensation expense, as a result of a significant increase in our stock price. The Company's share-based compensation fluctuates with our stock price. In the first quarter of 2013, our stock price increased approximately $15 per share compared to the stock price remaining flat during the same period in 2012.
Manufacturing earnings from operations were $43.8 million for the first quarter of 2013 compared to $34.1 million for the same period in 2012. This increase was due primarily to a higher mix of tank railcars as well as operating leverage and efficiencies achieved as a result of strong tank railcar production volumes, partially offset by lower hopper railcar shipments. The Company also continued to benefit from cost savings achieved by the vertical integration projects put in place during the past several years. Manufacturing earnings from operations for the first quarter of 2013 included $9.8 million of estimated profit on railcars built for the Company's lease fleet, which is eliminated in consolidation and is based on an estimated fair market value of revenues as if the railcars had been sold to a third party, less the cost to manufacture.