Chao Lu
Analyst · China Renaissance
Thank you, Kate, and hello, everyone. It has been an honor and a great pleasure to join RLX's management team [ to advocate ], value creation has been at the center of all our initiatives. Next, I will share some specifics regarding the initiatives we have taken in the first quarter. Then I will walk you through our financial results for the first quarter and our guidance for the second quarter.
In March, in response to user demand, we released a new product, [ RELX Lite ], also known as [Foreign Language], with more affordable pricing. We will keep expanding and enhancing our product offering as we seek to serve the diverse needs of our users in China.
We also continued our expansion of offline distribution networks and retail channels across the nation to further penetrate the e-vapor products amongst adult smokers. As of March 31, 2021, we've partnered with over 15,000 RELX Branded Partner Stores nationwide. And we are excited to see an increasing number of branded store partners willing to start business with us to open RELX Branded Partner Stores, working together to better serve adult smokers in China.
Meanwhile, as part of our consistent efforts to expand our industry-leading retail model nationwide, we have also been collaborating with various forms of retailers to diversify our distribution and retail network. In the first quarter of 2021, we opened our Quality Lab to further strengthen our quality assurance and control capability. We also started developing our second and third exclusive production plants to enhance our production capabilities.
In terms of our efforts in scientific research, the Journal of Applied Toxicology published RELX Lab's science study on the cooling agent WS-23. The peer-reviewed journal article formed part of our ongoing emphasis on scientific research. Looking ahead, we will keep investing in in-house lab research related to product quality and safety, physical chemistry, psychological and clinical elements and the evaluation of long-term use of e-vapor products.
Keeping up to our commitment to corporate social responsibility, we remain dedicated to building and strengthening our trusted brands by consistently adhering to our strong ethical principle. We have continued investing in the Golden Shield Program to combat sales of counterfeit products, having delisted over 100,000 online links and ceased over 170,000 counterfeit products.
In late April, we published our first ESP program, detailing our efforts and commitment to our stakeholders. Yesterday, after newly revised law on the protection of minors was enacted, we were the first amongst all our peers to call on the entire industry participants to thoroughly study the relevant laws and regulations and strictly abide by all.
Turning to financial performance. We started 2021 with good momentum as our first quarter results came in above our expectations. Our robust top line growth continued as a result of the expansion of our distribution and retail network, driving increased user penetration amongst adult smokers. We remain devoted to implementing our cost optimization strategy and enhancing operating leverage.
I will now provide a brief overview of our key financial results for the first quarter of 2021. Our net revenues increased by 48.2% to RMB 2.4 billion in the first quarter of 2021 from RMB 1.62 billion in the fourth quarter 2020. The growth was primarily due to an increase in net revenues from sales to offline distributors, which was driven by the expansion of our distribution and retail network.
Gross profit increased by 59.1% to RMB 1.1 billion in the first quarter of 2021 from RMB 694.1 million in the fourth quarter of 2020. Gross margin increased to 46% in the first quarter of 2021 compared to 42.9% in the fourth quarter 2020. Operating expenses were RMB 1.2 billion in the first quarter of 2021 compared to RMB 852.6 million in the fourth quarter of 2020.
Selling expenses increased by 48.2% to RMB 291.5 million in the first quarter of 2021 from RMB 196.7 million in the fourth quarter of 2020. The increase was mainly driven by, one, an increase in salaries and welfare benefits; two, an increase in branding material expenses; and three, an increase in shipping expenses.
General and administrative expenses increased by 59.5% to RMB 712.8 million in the first quarter of 2021 from RMB 447 million in the fourth quarter of 2020. The increase was primarily due to, first, an increase in salaries and welfare benefits; and second, an increase in share-based compensation expenses, partially offset by a decrease in legal and other consulting fees.
Research and development expenses increased to RMB 211.6 million in the first quarter of 2021 from RMB 208.9 million in the fourth quarter of 2020. The increase was primarily driven by an increase in salaries and welfare benefits, partially offset by, first, a decrease in share-based compensation expenses; and second, a decrease in material expenses.
Share-based compensation expenses recognized in selling expenses, general and administrative expenses and research and development expenses in total were RMB 877.5 million in the first quarter of 2021 and RMB 656.1 million in the fourth quarter of 2020.
Loss from operations was RMB 111.9 million in the first quarter of 2021 compared with RMB 158.5 million in the fourth quarter of 2020. Income tax expenses was RMB 176.3 million in the first quarter of 2021 compared with RMB 110.6 million in the fourth quarter of 2020, primarily due to an increase in taxable income.
GAAP net loss was RMB 267 million in the first quarter of 2021 compared with RMB 236.7 million in the fourth quarter of 2020. Non-GAAP net income reached RMB 610.5 million in the first quarter of 2021.
GAAP basic and diluted net loss per ADS were both RMB 0.174 in the first quarter of 2021 compared to RMB 0.165 in the fourth quarter of 2020. Non-GAAP basic and diluted net income per ADS were both RMB 0.398 in the first quarter of 2021 compared to RMB 0.292 in the fourth quarter of 2020.
As of March 31, 2021, the company had cash and cash equivalents, restricted cash, short-term bank deposits, short-term investments and long-term bank deposits of RMB 14.4 billion compared to RMB 3.4 billion as of December 31, 2020. The increase was primarily due to net proceeds raised in the company's IPO in January. As of March 31, 2021, approximately USD 1.65 billion, equivalent to RMB 10.8 billion that is denominated in U.S. dollars.
Now turning to guidance. For the second quarter of 2021, the company currently expects net revenue to exceed RMB 2.85 billion, and non-GAAP net income to exceed RMB 720 million. The above outlook is based on the current market conditions, including those related to COVID-19 pandemic and reflects the company's primary -- preliminary estimate of the market and operating conditions and user demand, which are all subject to change.
This concludes our prepared remarks today. We will open the call to questions. Operator, please go ahead.