We refer you to the forward-looking statements included in our press release and earnings presentation. This morning, we will review our financial results for the fourth quarter and full year 2025 and share our outlook for our key product lines and end markets. We delivered record annual production across both of our key ammonia and sulfuric acid unit operations. We invested $116 million in CapEx, funding key growth and enterprise initiatives, including our sustained growth program.
We anticipate continued strength in plant nutrients, supply-demand fundamentals, and expect acetone margins to remain near cycle averages, while nylon remains plateaued in its trough. In total, we anticipate roughly an $8 million-$10 million unfavorable earnings impact in the first quarter, which we do intend to fully offset as we progress through the year. This includes optimizing production output and sales volume mix, driving fixed cost reductions and productivity, maintaining a disciplined approach to cash management, and taking a risk-based approach to capital investment and plant turnaround scoping. Market-based pricing was favorable by approximately 2%, driven by the continued strength in plant nutrients, reflecting favorable North American ammonium sulfate supply and demand conditions, partially offset by lower acetone prices as anticipated.
adjusted EBITDA was $25 million, up $15 million from last year, while adjusted EBITDA margin was 6.9%. In Nylon Solutions, volumes declined sequentially as we moderated caprolactam and resin production rates to manage inventory in a softer demand environment. Granular ammonium sulfate volumes increased year-over-year, supported by the resiliency of sulfur nutrition demand and continued progress of our sustained growth program. I'm now on slide 6, where we've summarized our full year 2025 financial results.