However, our 24% depletions growth for the second quarter decelerated from our first quarter growth of 48% and was below our expectations as the hard seltzer category and the overall beer industry were softer than we had anticipated.
In measured off-premise channels in the first half of this year where our brand portfolio represented 4% of total industry volume, we delivered over 45% of industry volume growth.
The overall Truly brand growth rate improved to 2.7 times the hard seltzer category growth rate in the latest 13 weeks, resulting in a 4 point share gain and closing the share gap to the number one brand to single digits.
Based on information in hand, year-to-date depletions reported to the Company to the 28 weeks ended July 10, 2021 are estimated to have increased approximately 32% from the comparable weeks in 2020.
For the second quarter, we reported net income of $59.2 million, a decrease of $0.9 million or 1.6% from the second quarter of 2020.
Earnings per diluted share were $4.75, a decrease of $0.13 per diluted share from the second quarter of 2020.
Shipment volume was approximately 2.45 million barrels, a 27.4% increase from the second quarter of 2020.
Our second quarter 2021 gross margin of 45.7% decreased from the 46.4% margin realized in the second quarter of 2020, primarily as a result of higher processing and other costs due to increased production at third party breweries, partially offset by price increases and cost saving initiatives at company owned breweries.
Second quarter advertising, promotional and selling expenses increased by $61.3 million from the second quarter of 2020, primarily due to increased brand investments of $41.2 million, mainly driven by higher media, production and local marketing costs and increased freight to distributors of $20.1 million that was primarily due to higher rates and volumes.
General and administrative expenses increased by $3.3 million from the second quarter of 2020, primarily due to increases in external services and salaries and benefits costs.
Based on information of which we are currently aware, we are now expecting full year 2021 earnings per diluted share of between $18 and $22, a decrease from the previously communicated range of between $22 and $26.
Excluding the impact of ASU 2016-09, the actual results could vary significantly from this target.
We're currently planning increases in shipments and depletions of between 25% and 40%, a decrease from the previously communicated range of between 40% and 50%.
We're targeting national price increases per barrel of between 1% and 3%.
Full year 2021 gross margins are currently expected to be between 45% and 47%.
We plan increased investments in advertising, promotional and selling expenses of between $80 million and $100 million for the full year 2021, a decrease from the previously communicated range of between $130 million and $150 million.
We estimate our full year 2021 non-GAAP effective tax rate to be approximately 26 % excluding the impact of ASU 2016-09.
We're not able to provide forward guidance on the impact that ASU 2016-09 will have on our 2021 financial statements and full year effective tax rate, as this will mainly depend upon unpredictable future events, including the timing and value realized upon the exercise of stock options versus the fair value when those options are granted.
We're continuing to evaluate 2021 capital expenditures and currently estimate investments of between $180 million and $230 million, a decrease and a narrowing from the previously communicated range of between $250 million and $350 million.
We expect that our cash balance of $103 million as of June 26, 2021 along with our future operating cash flow and unused line of credit of $150 million will be sufficient to fund future cash requirements.

Summary:
Earnings per diluted share were $4.75, a decrease of $0.13 per diluted share from the second quarter of 2020.
We're not able to provide forward guidance on the impact that ASU 2016-09 will have on our 2021 financial statements and full year effective tax rate, as this will mainly depend upon unpredictable future events, including the timing and value realized upon the exercise of stock options versus the fair value when those options are granted.