As a result, our income statement is presented on a continuing operations basis.
As we look to 2022, we expect mid-single-digit revenue growth before Kyndryl and currency and $10 billion to $10.5 billion of free cash flow for the year.
We now have more than 3,800 hybrid cloud platform clients, which is up 1,000 clients from this time last year.
IBM Consulting continues to help drive platform adoption, with about 700 Red Hat engagements for the year.
As we move toward that, we had more than 50% revenue growth this year in partnerships with AWS, Azure, and Salesforce.
And today, we have nearly 3,000 active engagements.
This is the first quantum chip that breaks the 100-cubic barrier and represents a key milestone on our path toward building a 1,000-cubit processor in 2023.
We made five acquisitions in the fourth quarter and a total of 15 acquisitions in 2021.
We delivered $16.7 billion in revenue, 58% operating gross margin, operating pre-tax income of $3.5 billion, and operating earnings per share of $3.35 for continuing operations.
We had solid revenue performance, up nearly 9%.
This quarter, our revenue growth includes about 3.5 points from the new relationship.
Excluding this, IBM's revenue was up 5%.
In the fourth quarter, Software was up 10%, and Consulting was up 16%.
These are our two growth vectors and together represent over 70% of our annual revenue.
Infrastructure, more of a value vector, tends to follow product cycles and was up 2%.
The Software and Infrastructure growth each include nearly 5 points from the new Kyndryl relationship while there is no contribution to Consulting's growth.
For every dollar of hybrid platform revenue, IBM and our ecosystem partners can generate $3 to $5 of software, $6 to $8 of services, and $1 to $2 of infrastructure revenue.
This drives IBM's hybrid cloud revenue, which is up 19% for the year.
Post-separation, revenue from our full-stack cloud capabilities from Infrastructure up through Consulting now represents $20 billion of revenue or 35% of our total.
Our operating gross profit was up 3%, and the $3.5 billion of operating pre-tax profit was up over 100%.
First, the year-to-year pre-tax profit reflects $1.5 billion charge to SG&A last year for structural actions to simplify and optimize our operating model and improve our go-forward position.
Throughout the year, we have been aggressively hiring, with about 60% of our hires in Consulting.
We're ramping investment in our ecosystem, and we acquired 15 companies in 2021 to provide skills and technologies aligned to our strategy, including capabilities to help win client architecture decisions.
Regarding tax, our fourth-quarter operating tax rate was 14%.
This was up significantly from last year but roughly 2 to 3 points lower than what we estimated in October due to a number of factors, including the actual product and geographic mix of our income in the quarter.
Our full-year consolidated cash from operations was $12.8 billion, and free cash flow was $6.5 billion.
These are all-in consolidated results and include 10 months of Kyndryl and the cash paid for the 2020 structural actions and spin charges.
IBM's stand-alone or baseline free cash flow for the year was $7.9 billion, which is aligned to our go-forward business.
In terms of uses of cash for the year, we invested over $3 billion in acquisitions.
We continue to delever, with debt down nearly $10 billion for the year and over $21 billion since closing the Red Hat acquisition.
And we returned nearly $6 billion to shareholders in the form of dividends.
This results in a year-end cash position of $7.6 billion, including marketable securities and debt of just under $52 billion.
In aggregate, our worldwide tax-qualified plans are funded at 107%, with the U.S. at 112%.
Our hybrid cloud revenue in software is up 25% for the year to more than $8.5 billion.
And subscription and support renewal rates continue to grow again this quarter, contributing to a $700 million increase in the software deferred income balance over the last year.
Hybrid platform and solutions revenue was up 9%.
Red Hat revenue, all in, was up 21%.
Automation delivered strong revenue growth, up 15%.
Data and AI revenue grew 3%.
Security revenue declined modestly in the quarter driven by lower performance in data security, while revenue grew 5% for the year.
Putting this all together, our annual recurring revenue, or ARR, is now over $13 billion, which is up 8% this quarter.
Revenue was up 14%.
First, all of the growth in transaction processing came from the new Kyndryl commercial relationship, which contributed more than 16 points of growth.
Second, I'll remind you that we're wrapping on a very weak performance in the fourth quarter of last year, which was down 26%.
We expanded pre-tax margin by 12 points, including nearly 10 points of improvement from last year's structural actions.
Revenue grew 16% with acceleration across all three revenue categories.
Complementing this strong revenue performance, our book-to-bill was 1.2.
Consulting's hybrid cloud revenue grew 34% in the quarter.
For the year, cloud revenue is up 32% to $8 billion.
The Red Hat-related signings more than doubled this year and are now over $4 billion since inception.
This quarter, we added over 150 client engagements, bringing the total since inception to over 1,000.
Our Consulting's growth was led by business transformation, which was up 20%.
In technology consulting, revenue was up 19%.
Finally, application operations revenue grew 8%.
Our pre-tax income margin expanded about 8 points, including just over 9 points from last year's structural actions.
Revenue was up 2%.
The Kyndryl commercial relationship contributed about 5 points of growth, which is higher than we expected in October.
Hybrid infrastructure and infrastructure support revenue were up 2% and 1%, respectively, with pretty consistent contribution from the new Kyndryl relationship.
IBM Z revenue performance, now inclusive of both hardware and operating system, is down 4% this quarter.
And then in distributed infrastructure, revenue was up 7% driven by pervasive strength across our storage portfolio.
The pre-tax margin was up over 9 points but essentially flat, normalizing for last year's structural action.
We have a higher-growth, higher-value business mix, with over 70% of our revenue in software and services and a significant recurring revenue base dominated by software.
On top of that, in 2022, the new commercial relationship with Kyndryl will contribute an additional 3 points of growth spread across the first three quarters.
At current spot rates, currency is roughly a 2-point headwind to reported revenue growth for the year and 3 points in the first quarter.
For free cash flow, we expect to generate $10 billion to $10.5 billion in 2022.
Now in 2022, despite the fact we still have nearly $0.5 billion of impact from the charges, we're focusing on a traditional free cash flow definition.
The $10 billion to $10.5 billion reflects a year-to-year improvement driven by lower payments for the structural actions, a modest tailwind from cash taxes, working capital improvements, and profit growth resulting from our higher growth and higher value business mix.
In 2022, we expect growth at the low end of the mid-single-digit model and then another 5 to 6 points of revenue growth from our external sales to Kyndryl.
We have solid momentum in IBM Consulting revenue and expect this to continue into 2022 as we help clients with their digital transformations.
On top of that, we're planning for about 2 to 3 points from the external sales to Kyndryl in 2022.
These segment revenue and margin dynamics will yield about a 4-point year-to-year improvement in IBM's pre-tax operating margin for the full year and 2 to 3 points in the first quarter.
Bringing this all together, we expect mid-single-digit revenue growth before Kyndryl and currency and $10 billion to $10.5 billion of free cash flow for the year, both in line with our midterm model.

Summary:
As a result, our income statement is presented on a continuing operations basis.
We delivered $16.7 billion in revenue, 58% operating gross margin, operating pre-tax income of $3.5 billion, and operating earnings per share of $3.35 for continuing operations.
We have solid momentum in IBM Consulting revenue and expect this to continue into 2022 as we help clients with their digital transformations.