The $2.4 million, or 44.9% year-over-year improvement in 2010 fourth quarter operating income reflects the higher revenue as well as a 7.7% reduction in total operating expenses during the period. The 2010 fourth quarter operating expense reduction reflects a 10.0% decline in station operating expenses primarily due to an approximate $2.4 million reduction in costs at the Company's Miami-Fort Lauderdale market cluster largely related to the non-renewed sports programming rights. Corporate general and administrative expenses in the 2010 fourth quarter rose $0.4 million or 21.8% compared with 2009 fourth quarter levels.
Fourth quarter 2010 station operating income (SOI), a non-GAAP financial measure, rose $2.7 million, or 34.2%, to $10.4 million compared with the 2009 fourth quarter. On a same-station basis, fourth quarter 2010 SOI rose 24.5% to $10.4 million, from $8.4 million in the same period of 2009.
The growth in 2010 fourth quarter net income and net income per basic and diluted share reflect the rise in operating income in the period and a $0.2 million, or 6.2% reduction in interest expense as a result of lower outstanding credit facility balances which more than offset a $0.6 million, or 38.2% increase in income tax expense.
Please refer to the "Calculation of SOI," "Reconciliation of SOI to Net Income," "Calculation of Same- Station SOI," and "Reconciliation of Same-Station SOI to Net Income" tables at the end of this announcement for a discussion regarding SOI calculations.Commenting on the results, George G. Beasley, Chairman and Chief Executive Officer, said, "Fourth quarter 2010 same-station net revenue rose 9.1%, marking the strongest quarterly same-station top line growth we have generated since early 2005. Our fourth quarter same-station revenue growth reflects the improving industry environment and was driven by increases at many of our market clusters including Philadelphia, Miami, Las Vegas, Wilmington, Augusta and Fayetteville. With the Company's streamlined operating and cost structure, we are generating significant flow through from revenue growth and reflecting that strong operating leverage, fourth quarter same-station SOI increased 24.5% to $10.4 million, the highest level of fourth quarter SOI that we've achieved since the fourth quarter of 2006, while SOI margins rose to 39%, up from 34% in the fourth quarter last year.