Inventories rose 0.6 percent to $1.679 trillion, while sales rose 0.2 percent to $1.299 trillion.
The monthly figures adding up manufacturing and trade inventories were in line with the consensus forecast.
Inventories are up 3.1 percent from September 2012, while sales have risen 2.9 percent over the same period.
The total business inventories-to-sales ratio was 1.29, based on seasonally adjusted data, unchanged from a year earlier.
The ratio indicates how long it will take to sell existing inventory at current prices. As the ratio rises, it indicates manufacturers may have too much inventory on hand and may adjust by slowing production.