Overall, our sales were sequentially up 11% compared to the fourth quarter, with all regions and segments showing revenue growth.
The sequential increase was broad-based, with all segments and regions growing between 9% and 12%.
A year ago, we primarily saw the COVID impact in China, and you can see this impact in our current quarter, Asia Pacific sales growth of 31%.
EMEA and our global specialty businesses also showed strong growth and were up 14% and 12%, respectively, from a year ago.
I also want to point out that our ability to gain new piece of business and take market share also contributed to our performance as our analysis shows that we had total organic sales growth due to net share gains of approximately 3% in the first quarter of this year versus the first quarter of '20.
So we continue to feel good about our ability to deliver on our historical performance of consistently growing 2% to 4% above the market due to share gains.
Overall, our cost of raw materials have increased over 20% since the end of last year.
Synergy achievement also was a factor in our results as we achieved $18 million in the current quarter compared to $10 million last year.
However, our leverage ratio of net debt-to-adjusted EBITDA continued to improve from 3.2 times at the end of the year to 3.1 times to the end of the first quarter.
We will have a step change in our profitability, essentially complete our integration, cost synergies, continue to grow above the market by taking share and reach our targeted net debt-to-adjusted EBITDA leverage of 2.5.
GAAP measures and non-GAAP measures provided in our call charts on Pages 10 to 21, for reference.
Our record net sales of $429.8 million increased 14% from the prior year, which was primarily driven by higher volumes, including 3% from acquisitions and increases due to foreign exchange of approximately 3%.
APAC's net sales increase of 31% was the largest increase than the prior year, but this was mainly due to the initial impacts of COVID hitting China in the first quarter of last year versus the rest of the segments being impacted in the second quarter of last year.
EMEA also showed strong net sales growth of 14% due to a solid bounce back from COVID-19.
Americas and GSB had net sales growth of 4% and 12%, largely due to higher volumes, including the Coral acquisition made in December of last year, which helped offset some of the market pressures we are facing, such as the semiconductor shortage.
Gross margins were 36.3% for the quarter compared to 35.4% in the prior year.
But excluding onetime COGS increases related to acquisitions, these would have been 36.6% and 35.5%.
Notably, this 1% improvement year-over-year is really the benefit of strong execution of integration synergies, offsetting higher raw material costs that we incurred in the quarter.
SG&A was up $5.6 million compared to the prior year quarter, as we had additional costs associated with our recent acquisition of Coral and higher SG&A due to the impact of foreign exchange.
As you can see in chart eight, our quarterly adjusted EBITDA of $77.1 million grew 28% from the prior year, which drove an 8% increase in our trailing 12-month adjusted EBITDA to $239 million.
From a tax perspective, we had an effective tax rate of 24.2% in the quarter compared to a benefit of 31.1% in the prior year.
Excluding various onetime items in each period, our tax rate would have been reasonably consistent at 25% for the current quarter compared to 22% last year.
To note, we do expect both our second quarter and full year ETRs will be in the range of 24.5% to 26.5%.
So net -- our net GAAP earnings per share of $2.11 grew 53% compared to the prior year as our strong operating earnings and adjusted EBITDA, coupled with $3 million of lower interest expense due to lower borrowing rates were partially offset by a slightly higher tax expense.
As we look to the company's liquidity, summarized on Chart nine, our net debt of $749.6 million increased $32 million in the quarter, which was primarily driven by a $25 million acquisition of a tin-plating business for the steel end market, $7.1 million of dividends paid and $12.6 million of operating cash outflow.
Despite this increase in net debt, the company was able to improve its reported leverage ratio to 3.1 times as of the first quarter compared to 3.2 at the end of last year.
This includes prioritizing debt reduction while continuing to pay dividends and invest in acquisitions that provide growth opportunities, which make strategic sense, all while remaining committed to reducing our leverage below our targeted 2.5 times level by the end of this year.
Though, as Mike mentioned, we still maintain our previous floor guidance that we will see a greater than 20% increase in adjusted EBITDA in 2021 as compared to the $222 million we achieved in the prior year.

Summary:
Our record net sales of $429.8 million increased 14% from the prior year, which was primarily driven by higher volumes, including 3% from acquisitions and increases due to foreign exchange of approximately 3%.