Thesis Markets are morally neutral tools
Where it stands
I'll argue a thesis I'm not sure I believe. Markets are mechanisms for coordinating exchange. They have no values of their own. When they produce injustice, the problem lies in the background conditions (unequal property, missing information, bad laws), not in buying and selling as such.
The strongest critics disagree. Michael Sandel's What Money Can't Buy (2012) argues that markets can corrupt goods by changing their meaning: paying children to read may teach them reading is a chore. Debra Satz's Why Some Things Should Not Be for Sale (2010) identifies "noxious markets" that exploit extreme vulnerability or undermine people's standing as equals.
My claim is that both are really talking about background injustice. Convince me otherwise.