So there we were, poring over earnings releases and annual reports, because that’s what we do around here in our spare time, when we came upon Alaska Air Group ($ALK).

That’s when we noticed: the company’s earnings release for full-year 2017 results, filed on Jan. 25, 2018, proudly said net income was $1.028 billion, up 26.3 percent from the prior year.

But wait! On the full 10-K that Alaska Air filed on Feb. 15, it listed net income as $1.034 billion — $6 million more than the number it reported just 21 days earlier.

What happened? Take a look at how Alaska Air reconciled its non-GAAP net income on the earnings statement (at right), compared to its full income statement filed in the 10-K (at left). Look closely.

Do you see it? The “special tax (benefit)/expense” in the earnings release was reported as a $274 million benefit, but that number changed to $280 million by the time the 10-K was filed. That explains the $6 million increase in net income.

According to a footnote in the earnings release, the benefit arose from remeasuring deferred tax liabilities after Congress passed the corporate tax cut in 2017. Apparently that remeasurement was adjusted by the time the Form 10-K was filed. That is legal; numbers in earnings releases don’t have any liability attached to them and aren’t audited, and the amount isn’t material anyway.

Still, our Alaska Air discovery did make us wonder: What other discrepancies do companies have between the 8-K earnings release and the 10-K annual report?

Another good example comes from AmerisourceBergen ($ABC) and its results for fiscal 2017. When Amerisource filed its earnings release on Nov. 2, 2017, it clearly reported net income as $414.5 million. But in its Form 10-K, filed on Nov. 21, net income had dropped to $364.5 million — a decrease of $50 million, or 12 percent. Which is not an immaterial amount of money.

Upon closer inspection, we can see that Amerisource increased its expense for employee severance and litigation by $50 million; that’s the cause of the net income discrepancy. If you compare footnote disclosures in the earnings release and the 10-K (folks, always read the footnotes), we can see the $50 million is specifically an increase in litigation settlements, from $864.4 million to $914.4 million.

Then you can use our Interactive Disclosure page to pull up AmerisourceBergen’s discussion of legal matters and contingencies. It’s a long list, including subsidiaries tampering with syringes to dilute oncology medicines and pending opioid legislation.

We didn’t do a sentence-by-sentence comparison to pinpoint exactly which legal troubles pushed up the settlement budget by $50 million, but any analyst following AmerisourceBergen could. That’s what Calcbench lets you do.

And, as we can see from these two examples, analysts probably should, too. A lot can change between the earnings release and the 10-K.