An extensive list of these risks and uncertainties are identified in our annual report on Form 10-K for the fiscal year ended August 31, 2020, and other filings.
Altogether, the team delivered core operating income of $277 million on revenue of $7.2 billion, creating a core operating margin of 3.8% for the quarter.
For this year, we now anticipate core earnings per share to be in the range of $5.50 on revenue of $29.5 billion.
But most importantly, we're maintaining our outlook of 4.2% for core operating margin and increasing our outlook for free cash flow by 5% to $630 million.
In Q3, we saw continued strength with notable revenue upside during the quarter in mobility, cloud-connected devices, and semi-cap relative to our plan 90 days ago.
Given the additional revenue, I'm particularly pleased with the strong leverage we achieved during the quarter, which enabled us to deliver a solid core operating margin of 3.8%, approximately 30 basis points higher than expected.
Net revenue for the third quarter was $7.2 billion, approximately $300 million above the midpoint of our guidance range.
On a year-over-year basis, revenue increased 14%.
GAAP operating income was $240 million and our GAAP diluted earnings per share was $1.12.
Core operating income during the quarter was $277 million, an increase of 61% year over year, representing a core operating margin of 3.8%, a 110-basis-point improvement over the prior year.
Net interest expense in Q3 was $36 million and core tax rate came in at approximately 18%.
Core diluted earnings per share was $1.30, a 251% improvement over the prior-year quarter.
Revenue for our DMS segment was $3.6 billion, an increase of 21% on a year-over-year basis.
Core margins for the segment came in at 3.9%, 140 basis points higher than the previous year.
Revenue for our EMS segment also came in at $3.6 billion, reflecting strong year-over-year growth in our cloud and semi-cap businesses.
Core margins for the segment were 3.8%, up 90 basis points over the prior year, reflecting solid execution by the team.
Cash flows provided by operations were $585 million in Q3 and capital expenditures net of customer co-investments total $197 million.
We exited the quarter with cash balances of $1.2 billion.
We ended Q3 with committed capacity under the global credit facilities of $3.8 billion.
With this available capacity, along with our quarter-end cash balance, Jabil ended Q3 with access to more than $5 billion of available liquidity, which we believe provides us ample flexibility.
During Q3, we repurchased approximately 2.5 million shares for $130 million.
At the end of the quarter, $124 million remain outstanding in our current stock repurchase authorization and we intend to complete this authorization during Q4 as we remain committed to returning capital to shareholders in FY '21 and beyond.
DMS segment revenue is expected to increase 11% on a year-over-year basis to $3.95 billion.
EMS segment revenue is expected to be $3.65 billion, a decrease of 2% on a year-over-year basis.
We expect total company revenue in the fourth quarter of fiscal 2021 to be in the range of $7.3 billion to $7.9 billion for an increase of 4% on a year-over-year basis at the midpoint of the range.
Core operating income is estimated to be in the range of $280 million to $340 million for a margin range of approximately 3.8% to 4.3%.
Core diluted earnings per share is estimated to be in the range of $1.25 to $1.45.
GAAP diluted earnings per share is expected to be in the range of $1 to $1.20.
For FY '21, we expect core operating margins to be 4.2% on revenue of approximately $29.5 billion.
This improved outlook translates to core earnings per share of approximately $5.50.
And importantly, we now expect to deliver more than $630 million in free cash flow despite the stronger growth.

Summary:
Altogether, the team delivered core operating income of $277 million on revenue of $7.2 billion, creating a core operating margin of 3.8% for the quarter.
For this year, we now anticipate core earnings per share to be in the range of $5.50 on revenue of $29.5 billion.
GAAP operating income was $240 million and our GAAP diluted earnings per share was $1.12.
Core diluted earnings per share was $1.30, a 251% improvement over the prior-year quarter.
We expect total company revenue in the fourth quarter of fiscal 2021 to be in the range of $7.3 billion to $7.9 billion for an increase of 4% on a year-over-year basis at the midpoint of the range.
Core diluted earnings per share is estimated to be in the range of $1.25 to $1.45.
GAAP diluted earnings per share is expected to be in the range of $1 to $1.20.