I'll start today with a brief operational update, including our ongoing actions in response to the COVDI-19 pandemic, as well as what we're seeing across our business in this fluid environment.
By month, organic daily sales declined by a high-teens percentage rate year-over-year during April and May, followed by a low 20% decline during June, despite a slight sequential improvement in daily sales rates.
In addition, while we are selling greater amounts of safety and janitorial supplies to customers, given COVID-19, this product category represents a small portion of our business and was less than 5% of our overall sales during fiscal 2020.
To provide more detail on our fourth quarter results, consolidated sales decreased 17.9% over the prior year quarter.
Acquisitions contributed 1.5% growth, partially offset by an unfavorable foreign currency impact of approximately 1%.
Netting these factors, sales decreased 18.4% on an organic basis, with a like number of selling days year-over-year.
Turning to sales performance by segment, as highlighted on slide 7 and 8 in the deck, sales in our service center segment declined 22.3% year-over-year or 21.1% on an organic basis.
Within our fluid power and flow control segment, sales decreased 6.8% over the prior year quarter, with our August 2019 acquisition of Olympus Controls contributing 5 points of growth.
On an organic basis, segment sales declined 11.8%, reflecting lower fluid power sales within industrial OEM, and mobile off-highway applications, as well as weaker flow control sales from slower project activity.
Moving now to margin performance, as highlighted on page 9 of the deck, gross margin of 28.7% declined approximately 40 basis points year-over-year or roughly 70 basis points, when excluding non-cash LIFO expense of $0.8 million in the quarter.
This compared favorably to prior year LIFO expense of $3.4 million.
Turning to our operating costs; on an adjusted basis, selling, distribution and administrative expenses declined 13.8% year-over-year, excluding $1.5 million of non-routine costs in the quarter, $1 million of which was recorded in our service center segment and $0.5 million in our fluid power and flow control segment.
Adjusted SG&A expense declined nearly 16% over the prior year on an organic basis, when excluding operating costs associated with our Olympus Controls acquisition.
as well as staffing alignments, implementation of furloughs and pay reductions and the temporary suspension of the company's 401(k) match.
Adjusted EBITDA in the quarter was $64.8 million, down roughly 26% compared to $87.6 million in the prior year quarter, while adjusted EBITDA margin was 8.9% or 9%, excluding non-cash LIFO expense in the quarter.
On a GAAP basis, we reported net income of $30 million or $0.77 per share, which includes the $1.5 million of previously referenced non-routine costs on a pre-tax basis.
On a non-GAAP adjusted basis, excluding these costs, we reported net income of $31.1 million or $0.80 per share, down $39.8 million or $1.02 per share respectively in the prior year quarter.
Moving to our cash flow performance and liquidity; during the fourth quarter, cash generated from operating activities was $127.1 million, while free cash flow was $123.2 million, or nearly four times adjusted net income.
For full year fiscal 2020, we generated record free cash flow of $277 million, representing 186% of adjusted net income and up over 70% from $162 million in the prior year.
Given the strong cash flow performance in the quarter, we ended June with nearly $269 million of cash on hand, with over 80% of that unrestricted U.S. held cash.
Our net debt is down 22% over the prior year, and net leverage stood at 2.3 times adjusted EBITDA at quarter end, below the prior quarter level of 2.5 times and the prior year level of 2.6 times.
During July, we utilized excess cash to pay off a $40 million private placement note that came due.
The paydown of the note, which had a 3.2% fixed rate, will drive additional cash interest savings into fiscal 2021.
We have now paid down roughly $170 million of debt since early 2018, including $55 million within the past seven months.
In addition, our revolver remains undrawn, with approximately $250 million of capacity, and additional $250 million accordion option, combined with incremental capacity on our uncommitted private shelf facility, we remain in a positive liquidity position.
Visibility remains limited on how customers will proceed with operations, particularly if an additional wave of infections materializes into the fall and winter months.
With that as a backdrop, assuming underlying demand remains consistent with July and early August trends for the remainder of the quarter, we expect fiscal first quarter 2021 sales to decline 17% to 18% organically year-over-year.
Lastly, we believe an effective tax rate of 23% to 25% remains an appropriate assumption near term.
Our capital and capex requirements remain limited, with fiscal 2021 targeted at $15 million to $20 million of capital spend.
We remain confident in our cash generation potential going forward, and reiterate our normalized annual free cash target of at least 100% of net income.
Long term, we remain committed to our financial targets of $4.5 billion in sales and 11% EBITDA margins.
To our customers and suppliers, our message is clear, we are the leading stand-alone distributor of industrial motion power and technologies, with growing capabilities across next generation automation and industry 4.0 solutions.

Summary:
On a GAAP basis, we reported net income of $30 million or $0.77 per share, which includes the $1.5 million of previously referenced non-routine costs on a pre-tax basis.
On a non-GAAP adjusted basis, excluding these costs, we reported net income of $31.1 million or $0.80 per share, down $39.8 million or $1.02 per share respectively in the prior year quarter.
Visibility remains limited on how customers will proceed with operations, particularly if an additional wave of infections materializes into the fall and winter months.