We are just about at the halfway point for earnings. They are excellent, and guidance is also strong for the second quarter, but a new concern has started to emerge on the company conference calls following the reports: higher inflation.

The main topic was commodity inflation around higher metal prices (aluminum and steel) and higher oil prices, which translated into higher packaging costs for many companies, but it also included wage concerns.

Earlier in the week, we heard from Caterpillar, which said it expects "steel and other commodity costs to be a headwind all year." 3M was seeing higher-than-anticipated costs for transportation and raw materials derived from crude oil. Kimberly-Clark said margins were "impacted by significant commodity inflation." Whirlpool said "significant raw material inflation" impacted margins. Procter & Gamble said, "Higher commodity costs reduced core earnings per share growth by approximately five percentage points."

This theme has continued among companies reporting in the last 24 hours:

Ford noted that its lower EBIT (earning before interest and taxes) was caused by commodity cost increases (metals) of about $480 million.

Ingersoll Rand (heating and air conditioning): "Inflation was higher than we planned and a significant headwind to margin expansion."

Packaging Corp. of America (container products): anticipates continued price inflation in chemical and freight costs, incremental wage pressure with a tighter labor market.

Avery Dennison (packaging materials) saw price increases for petrochemicals and paper.

Allegion (locks, key systems) said that its operating margin of 17 percent decreased 150 basis points, driven by inflationary pressure, and added, "We expect inflationary pressures to continue throughout the year."

While commodity inflation was the main topic, several companies also brought up higher wages. Chipotle said wages were up 5 percent and that they expect it will continue to rise.

Several companies emphasized they were raising prices in response to higher costs, including Ingersoll Rand and Avery Dennison. A.O. Smith (water heaters, air purification products) said that "As a result of significantly higher steel prices and inflation in freight and other costs, we announced a price increase up to 12% on U.S. water heater products effective in early June."

Others are trying to make up for higher costs by improving productivity. Stanley Black & Decker said that "to the extent that price does not necessarily cover all of the inflation, it is still possible to have margin accretion in this business because of the productivity that we consistently generate..."

But not everyone can raise prices.

Goodyear Tire said it incurred an additional $50 million in raw material costs in the quarter, and noted that, "we're not going to have the opportunity to immediately recover a significant portion of those added cost pressures in pricing."

And for those that can't raise prices — which includes many consumer companies--that means margins can be under pressure. Inflation does appear to be having some impact on margins. UBS noted that among companies that have reported earnings, margins have contracted among several sectors, including autos (down 0.2 percent), consumer durable/apparel (down 0.1 percent), tech hardware (down 1.1 percent), and household personal products (down 0.2 percent).

Those are all sectors impacted by higher commodity costs.