What are the Risks of Arbitrage?

There are certain risks associated with arbitrage. These can range from low to high risk, depending on the transactions.
The securities market tends to have lower risk because it is not possible to close down two to three such transactions simultaneously. However, it is possible to close just one section a deal, though any shift in the market prices would make it impossible to close the remaining section and get a profit.
Another risk type is counter-party, whereby either the seller or buyer does not complete their side of the bargain as promised. In fact, the risk level gets much higher when borrowed funds or leverage are used.