There was a lot of action in 2021 in enterprise M&A — once totaled, my top 10 deals came in at just under $121 billion. And the biggest enterprise deal of the year by far — Oracle’s bid to buy Cerner — happened as I was writing this post.

The final tally doesn’t include what would have been the third largest deal when Zoom agreed to buy Five9 last summer for $14.7 billion. That deal eventually broke down, as Zoom’s pandemic stock price bubble burst, and the companies ultimately decided to go their separate ways.

Meanwhile the second-biggest deal, Microsoft’s bid to buy Nuance Communications is stuck in regulatory limbo in the U.K., as regulators worry that it could give Microsoft too much power in the healthcare market. The U.K. decision bears watching, given that Visa’s $5.3 billion acquisition of Plaid was scuttled last year when U.S. authorities sued to block the deal and the parties eventually decided to walk away.

You may recall that last year’s total was an incredible $165 billion, but that was fueled by four large-chip consolidation deals totaling over $100 billion. This year’s deals are far more diverse, with more than 20 deals over $1 billion, and many that didn’t make this list. In 2019, the bottom three were under $2 billion — this year, the smallest deal was $5.4 billion.

It’s also worth noting that four or the 10 deals involved private equity firms, who continue to be highly active in the M&A market. There was a big focus on legacy security companies this year.

As in previous years, I needed to decide which deals belonged on my list and which didn’t, and that’s never easy to do. I didn’t include a number of large deals, including the $29 billion Square-Afterpay merger or the $14 billion McAfee deal, as they both involved consumer-focused businesses.

I also excluded a couple of other big companies that fall outside my coverage area. These included the Hitachi-Global Logic deal for $9.6 billion, and the Panasonic-Blue Yonder deal for $7.1 billion. Two other big deals just missed making the list: the $5.3 billion KKR-Cloudera acquisition and the Cisco-Acacia $4.5 billion deal.

So here are my top 10 deals in ascending order:

10. Clearlake-Quest Software $5.4B

In the first of a string of private equity companies buying older security companies, Clearlake bought Quest Software for a reported $5.4 billion from another private equity firm, Francisco Partners. Quest, whose products include One Identity and OneLogin, has been shuffled around over the years, but it still has a decent business, and Francisco was able to turn a tidy profit on its 2016 $2 billion investment.

9. Permira-Mimecast $5.8B

Speaking of private equity, Permira took a plunge into email security with the acquisition of London-based Mimecast earlier this month for $5.8 billion. Permira liked that Mimecast had a large existing market with almost 40,000 customers, half of who use Microsoft Office 365 products.