This report is the result of the first large survey of maize traders in Nigeria in the past several decades. The sample of 1943 traders covered one state in the South and four in the North, with traders in city wholesale markets and regional markets. We surveyed assets and behavior in 2011 and five years later. The key findings are as follows. First: interesting findings about the structure of the segment. The average trader is a substantial SME – grossing 440,000 dollars per year in the North and 70,000 in the South. But the overall maize trade segment is quite concentrated – with a Gini coefficient of 70%. Traders are mainly specialized in trading rather than trading and farming (none engage in maize production in the South and just 40% of them in the North with own maize, forming only 10% of their trade). Traders also specialize in maize (accounting for about 70% of their volumes) and in wholesaling (taking possession) rather than brokering (for a fee). Second: interesting and surprising findings with respect to the client and spatial configuration of the segment. The maize supply chain is North-North and North-South. It depends overwhelmingly on the North, with even the Southern traders buying 80% of their maize from the North. Surprisingly, compared to the traditional view of wholesalers buying from rural brokers and thus being long and fragmented, it is partially “dis-intermediated”, with Northern urban traders buying 50% of their maize from farmers, and Southern urban traders buying 60%. Further, 80% of maize is sold by the traders to other traders and retailers, and only about 20% to feed and flour mills. The latter are still an emerging sector. In all these exchanges, contracts cover only a tiny share, about 5%. Third, our survey provides insights into the conduct of trading sector that contrasts with the traditional view. Traders own very little of the transport and warehousing they use. In the main they rely on a well-developed 3PLS (third party logistics service) sector market, and a warehouse rental market. Moreover, traders buy the great majority of maize (except for the minority they produce as farmers) already bagged. Thus, few traders dry or fumigate the maize. Most traders label the bags with their own information, but then often ship the maize in mixed lots with other traders in 3PLS trucks. Few traders (only 24%) store their maize, and then only for a short time. We found there is extremely little waste/loss of maize in their handling of the bags. Fourth, we find that a long-held view of traders advancing funds or inputs to farmers (or other traders) to “tie output with credit” is simply not the case among maize traders in Nigeria today. We find that to be near absent – 6% of transactions in the South, 10% in the North, for advance of funds, and 0% for advance of inputs. We turn to the policy implications of our findings.