Walmart utilize some pretty underhanded tactics against their suppliers. At least they did back in the 90s and I have reason to believe they still do.
One example: Place a massive order beyond the capability of the supplier to meet the demand but at a premium price to incentivize them to try anyway. Then cancel at the last minute when production is almost finished but doesn't quite meet the original quantity ordered. Finally come back a few weeks / months later and offer to buy the resulting overstock at a deeply discounted price.
Obviously the blame doesn't all belong to Walmart but when a company is struggling and desperate it only takes a couple of deals like that to put them on a fast track to liquidation of their assets until all that remains is a company dedicated to marketing imported products under a previously prestigious brand.
The company I have specific knowledge about, Rawlings Sporting Goods, shut down most of their US manufacturing at the end of the 1990s and moved everything to China. Walmart had a big hand in driving the nails in the coffin of that ~80 year old company.
