Thank you, Laura, and I'd like to welcome everyone to our 2015 first quarter results conference call. I'll be reviewing the financial results in detail and then Bob will provide color on our markets and what we are seeing in our customer base, and then I'll be back to give guidance for the second quarter.
First quarter 2015 end user net revenues were unchanged sequentially at $9.4 million or 92% of net revenues compared to 95% of net revenues in the fourth quarter of 2014. OEM net revenues were $793,000 or 8% of net revenues, up from $504,000 or 5% for the fourth quarter of 2014. Net revenues from markets outside of semiconductor tests were $1.8 million or 18% of net revenues compared with $3.4 million or 34% of net revenues in the fourth quarter.
The company's gross margin for the first quarter was $4.9 million or 48% as compared with $5.0 million or 51% in the fourth quarter. The decline in the gross margin was the result of an expected increase in our component material costs, which grew from 30.7% in the fourth quarter to 33.8% in the first quarter. In addition, our fixed manufacturing cost increased in absolute dollars of $80,000 or 6% sequentially to $1.5 million, while remaining fixed as a percentage of our net revenue at 15%.
The increase in our consolidated component material costs in the first quarter was driven by increases in our Mechanical and Thermal Products segments. Our Mechanical Products segments component material costs increased from 36.3% in Q4 to 44.9% in Q1, while our Thermal Products segment saw its component material costs grow slightly from 28.3% in Q4 to 28.5% in Q1. The increase in component material costs in both segments was driven by changes in product and customer mix. Our Electrical Products segments component material costs remain steady at 34.3% for both Q4 and Q1.
The increase in our fixed manufacturing cost in the first quarter were driven by increased facility costs due to snow removal cost associated with the harsh winter on the East Coast of U.S. and higher levels of real estate taxes. There were also increases in business insurance costs and benefit costs for operational staff.
Selling expense was $1.5 million for the first quarter compared to $1.4 million for the fourth quarter, an increase of $70,000 or 5% sequentially. The increase was due to higher levels of sales commission expense, resulting from the increased sales levels in the first quarter compared to the fourth quarter, partially offset by reductions in product warranty expenses in our Thermal Products segment and installation costs in our Mechanical Products segment.
Engineering and product development expense was $972,000 for Q1 compared to $876,000 for Q4, an increase of $66,000 or 8%. The increase was a result of higher levels of salary and benefits expense driven by the full quarter impact of the costs of additional staff added in our Mechanical and Electrical Product segments during the fourth quarter, as well as higher levels of spending on patent legal costs. These increases were partially offset by reduced product development costs in our Thermal and Electrical Products segments.
General and administrative expense for the first quarter was $1.8 million compared to $1.6 million for the fourth quarter, an increase of $257,000 or 17%. As noted in our earnings release, first quarter 2015 G&A expense included $320,000 of costs related to our due diligence efforts and transaction related costs associated with the potential acquisition. Adjusted for these non-recurring expenses, our general and administrative expense would have declined $63,000 or 4% sequentially due to reduced spending on professional fees, director fees, and corporate travel.
Our due diligence efforts on the potential acquisition are not yet complete, and certain criteria which will impact our final decision with regard to consummating this transaction will not likely be known until the target company's second quarter results are complete. While counsel has advised us that we are not able to comment further on the status of this potential acquisition opportunity at this time, I would like to update investors on our acquisition related efforts over the last year.
We retained an acquisition advisor at the beginning of the first quarter of 2014. And since that time we've considered approximately 50 different acquisition opportunities. The current potential acquisition is not the first opportunity we have proceeded with since retaining our acquisition advisor and during the second half of 2014 two other acquisition opportunities proceeded to the letter of intent stage; however, in both of those cases, we chose to not move forward after completing some due diligence.
The inTEST senior management team is very focused on identifying and reviewing acquisition opportunities that would create shareholder value, and we have a strong track record of the integrating businesses that expand either our market share or product offerings. We have been actively investing in growth adding five companies to our operations since 1998; a very successful track record of acquisitions that have broadened our growth opportunities.
Our goals for future acquisitions are that they be accretive within one quarter of acquisition, provide access to markets outside of the semiconductor market which create stronger revenue growth opportunities, and that they be complementary to our existing businesses. The acquisition process can use significant portions of our time and resources, and we will continue to look to leverage our considerable financial flexibility as suitable inorganic growth opportunities arise.
Now back to the Q1 financial results. Other expense was $11,000 for the quarter compared to $8,000 for the fourth quarter. We accrued income tax expense of $233,000 during the first quarter compared to $217,000 booked in the fourth quarter. Our effective tax rate was 35% in the first quarter compared to 19% in the fourth quarter. The lower effective tax rate in the fourth quarter was driven by two factors, the approval during the quarter of the U.S. R&D tax credit and our recording of the year-to-date impact of that credit, as well as recording a reduction in the valuation allowance we carried against our German deferred tax asset.
At March 31, 2015 our deferred tax assets were $1.4 million unchanged from the level at December 31, and our remaining net loss carry-forward at March 31 was $1.4 million for domestic states, primarily California, and $1.1 million for foreign related to our German operations.
First quarter net income was $438,000 or $.04 per diluted share compared with fourth quarter net income of $959,000 or $.09 per diluted share. Average shares outstanding were 10,484 at March 31. If one adds back the $320,000 of non-recurring costs associated with potential acquisition, net of related income tax expense, first quarter earnings per share are $.07 per diluted share.
Amortization and depreciation expense was $200,000 for the first quarter and EBITDA was $869,000 for the first quarter, down from $1.4 million in EBITDA for the fourth quarter. Consolidated headcount at the end of March, which includes temporary staff was 129, down one from the level we had at December 31.
I will now turn to the balance sheet. Cash and cash equivalents at the end of the first quarter were $22.5 million, down $641,000 from December 31 due to the payment of various accruals during the first quarter. We currently expect cash and cash equivalents to increase throughout 2015 excluding the impact of the closing of any acquisition.
Accounts receivable increased during the quarter by $1.4 million to $6.5 million at March 31. The increase was driven by increased shipments during the first quarter. Inventory increased slightly by $396,000 to $4.2 million at March 31. Capital expenditures during the first quarter were $179,000, down from $295,000 in the fourth quarter and primarily represented additions to lease the systems in our Thermal Products segment. Bob will provide consolidated and segment booking data later in the call and the backlog at the end of March was $5.0 million up from $3.8 million at the end of December.
I'll now turn the call over to Bob.