SAN DIEGO, Feb. 5 /PRNewswire-FirstCall/ -- ResMed Inc. (NYSE: RMD) today announced record revenue and income for the quarter ended December 31, 2008. Revenue for the December 2008 quarter was $223.0 million, a 10% increase (a 16% increase on a constant currency basis) over the quarter ended December 31, 2007. For the quarter ended December 31, 2008, income from operations was $43.3 million and net income was $33.9 million, an increase of 18% and 26%, respectively, compared to the quarter ended December 31, 2007. Diluted earnings per share for the quarter ended December 31, 2008 were $0.44, an increase of 29% compared to the quarter ended December 31, 2007.
SG&A expenses were $70.1 million for the December 2008 quarter, an increase of $2.4 million, or 4% (a 14% increase on a constant currency basis) over the same period in fiscal 2007. SG&A expenses were favorably impacted by the appreciation of the U.S. dollar against international currencies. This increase in SG&A was primarily due to expenses necessary to support sales growth. SG&A costs were 31% of revenue in the December 2008 quarter, compared to 33% in the same period in fiscal 2007.
R&D expenses were $14.9 million for the December 2008 quarter, or approximately 7% of revenue. R&D expenses were flat (a 27% increase on a constant currency basis) compared to the prior year quarter. R&D was also positively impacted by the appreciation of the U.S. dollar against international currencies, particularly the Australian dollar. R&D outlays reflect ResMed's continuing commitment to innovation within its product portfolio, as well as an ongoing commitment to clinical research and product development.
Amortization of acquired intangibles of $1.7 million ($1.1 million net of tax) incurred during the quarter ended December 31, 2008, consisted of amortization of assets associated with our acquisitions of Resprecare, Hoefner, Saime and PolarMed. Stock-based compensation costs incurred during the quarter ended December 31, 2008 of $6.8 million ($4.9 million net of tax) consisted of expenses associated with stock options granted to employees and our employee stock purchase plan.
During the December 2008 quarter, we donated $1.0 million ($0.6 million, net of tax) to the ResMed Foundation. The Foundation was established primarily to promote research into the deleterious medical consequences of untreated sleep-disordered breathing.
For the six months ended December 31, 2008, revenue was $440.9 million, an increase of 14% over the six months ended December 31, 2007. For the six months ended December 31, 2008, income from operations and net income were $79.9 million and $61.9 million, an increase of 16% and 21%, respectively, compared to the six months ended December 31, 2007. Diluted earnings per share for the six months ended December 31, 2008 were $0.80 per diluted share, an increase of 23% compared to the six months ended December 31, 2007.
Inventory, at $143.1 million, decreased by $15.2 million compared to June 30, 2008. Accounts receivable days sales outstanding, at 76 days, increased by 4 days compared to June 30, 2008.
Kieran T. Gallahue, President and Chief Executive Officer, commented, 'In the second quarter of fiscal 2009, we continued to show strong growth year over year. Sales in the Americas totaled $123.1 million, a 23% increase over the prior year quarter, while sales outside the Americas were $99.9 million, a decrease of 3% over the prior year quarter.
