Also, please note that during this conference call, we may discuss certain non-GAAP financial measures as we review the company's performance. One of these non-GAAP measures is EBITDA, which is defined as earnings before interests, taxes, depreciation and amortization. A second non-GAAP measure is adjusted EBITDA, which excludes charges related to store closures. We use these measurements as part of our evaluation of the performance of the company. In addition, we believe these measures provide useful information to investors. Please refer to the appendix within the Investor Relations presentation for a reconciliation of these non-GAAP measures to the most comparable GAAP financial measures. I will now turn the call over to Theo.
Thank you, Roxane, and good morning, everyone, joining us on the call today as we report our fourth quarter and fiscal year 2012 results. If you're following along with the slide presentation posted on our website, please turn to Slide 3. I'll begin by providing some texture to our financial results for the quarter and for the fiscal year, and then I'll outline our strategic focus for 2013. Starting with our fourth quarter, we delivered an 8.3% comparable store sales increase on top of a 9.8% increase in the same period last year. Importantly, this was our seventh quarter in a row of positive comps and our third consecutive quarter of achieving a positive comp on top of a prior year positive comp. In the quarter, we accelerated our progress towards returning the business to profitability. Our gross margin improved by 30 basis points, and our operating margin improved by 450 basis points. And as we continue to grow our top line, we gained further leverage on SG&A expenses.
Finally, as we announced last month, we significantly improved our capital structure by refinancing our debt. This increased our liquidity, modified our covenants and will substantially lower our annual interest expense. We believe that these results are a clear affirmation of our accomplishments over the past 2.5 years. Essentially the same constituents that evaluated our business in 2010, our bank group and Golden Gate Capital concluded that our business is now stronger, healthier and that we've made important progress towards returning the business to profitability.