Profit data has pretty much acted as we’ve been suggesting it would since 2007. Companies have a lot of say in terms of when to earn their profit. Of course, all companies want more profit and profit is hard to earn, but I'm talking about the timing of it. When a company wants to defer profit, they can defer activity or engage in any number of accounting maneuvers in order to move things around. Most of them are quite legal.
The data below show that business managers are fairly adept at this skill of moving profit out of non-desirable time periods (such as the 2nd half of 2017 when tax cuts had not yet kicked in) and into early 2018 (when they finally had kicked in). So, profits were suppressed in 2017 and then spiked in 2018. They appear to have peaked in the 3rd quarter of 2018. How do we know? We don't, but a large proportion of the largest profit companies told us so in the 3rd quarter. They announced record profits, and then told markets not to get too used to those kind of high-profit growth figures. That was one of the major drivers of the 4th quarter sell-off in markets: 3rd quarter profits announced in tandem with management's attempts to tamp down expectations.
So, the reported profits harmonize with reported GDP, as well as with Gross Output, markets, and coincident indicators (more on those last two later) in predicting a slowing (but not contracting) economy.