Netting and CSA Agreements

Two banks might have 200 different derivatives trades open with each other at any time — some in one bank's favor, some in the other's. Without any agreement, if one bank defaulted, the surviving bank would have to pay out on every trade where it owed money, while standing in line as an unsecured creditor for every trade where it was owed money. That asymmetry is a huge, avoidable source of risk, and it's exactly what netting agreements and CSAs exist to fix.

From gross to net

A master netting agreement — typically an ISDA Master Agreement — establishes that, if either party defaults, all outstanding trades between the two are settled as a single net amount rather than trade by trade. If Bank A owes $30 million across some trades and is owed $22 million across others, netting means the real exposure is just $8 million, not $52 million of gross obligations flying in different directions.

The CSA: collateralizing the net number

A netting agreement tells you what the exposure is; a Credit Support Annex (CSA) is the contract that says what to do about it. Under a CSA, whichever party is net "out of the money" posts collateral — usually cash or high-quality bonds — to the other, and that collateral is reset (called a margin call) on a regular schedule, often daily. If the net exposure rises to $8 million, the losing side posts roughly $8 million of collateral; if it later shrinks to $3 million, some collateral flows back.

Worked example

Bank A and Bank B trade 15 FX forwards and interest-rate swaps. Marked to market today, A owes B $18 million on some trades and B owes A $11 million on others. Under their netting agreement, the net exposure is $7 million in B's favor. Their CSA requires daily variation margin, so A posts $7 million of cash to B. The next day, rates move and the net figure shifts to $4 million in B's favor; $3 million of that collateral is returned to A. At no point does either side carry more than a day's worth of unsecured net exposure.

What this means in practice

Netting and CSAs are why the derivatives market can function at the scale it does: without them, every bank would need vastly more capital to absorb gross counterparty exposures. The catch is legal, not financial — netting only works if it's enforceable in the counterparty's home jurisdiction bankruptcy code, which is why banks maintain legal opinions on netting enforceability country by country before booking trades there.