Manufacturing growth sped up slightly for May, according to an Institute for Supply Management (ISM) report released today. ISM updated its numbers twice today after noticing a software error, with the most recent figure showing faster growth than the first one released this morning. 

After April's reading clocked in at 54.9%, May's index came in at 55.4%. Based on surveys of purchasing managers, a reading above 50% indicates that the manufacturing economy is generally expanding, while below 50% indicates that it is generally contracting.

Market watchers were taken for a spin earlier today, when the ISM published an incorrect index reading -- twice. But its final reading, 55.4%, aligned almost exactly with analyst expectations of 55.5%. The original, erroneous number from this morning showed growth slowing and missing expectations.

"We have recalculated and confirmed that the actual index indicates that the economy is accelerating," ISM said in a statement. It said it is looking into how the error occurred.   

ISM Purchasing Managers Index Chart

On a component-by-component basis, the all-import new orders indicator increased 1.8 points to 54.9% as production jumped 5.3 points to reach 61%. Employment growth shaved off 1.9 points, but its 52.8% reading marks the 11th straight month of employment growth.

As overall growth rates improved, not a single industry reported manufacturing contraction for May. Furniture and electric equipment industries recorded the strongest growth rates, while plastics and rubber products claimed the slowest growth rate.