I am adding on to @noob2 answer -- which, is correct if expressing exposures as a value of the fund's base currency. E.g., Fund XYZ has $1M of short equity exposure.
When calculating a portfolios total exposure, should the value of the
cash accounts be included?
For exposures expressed as a percentage of assets, the denominator of that calculation does indeed include cash and cash equivalents. Exposure's expressed as a percentage of assets are more informative when understanding a fund's risk.
For example, a fund with $1M of short equity exposure and no other risky positions is said to be 1M short. This information alone doesn't tell you much about the fund's risk appetite except that they have 1M at risk. On the other hand, saying a fund is 1% short is much more informative about the risks that the fund is taking.
This doesn't match with bank accounts as I see it, and so I would not
want to include the value of bank accounts in looking at a portfolios
Just because a 100M fund has 1M of short equity exposure in a brokerage account and the other 99M sitting in a bank in cash or cash equivalents doesn't mean it's not AUM. It's all AUM and all of it needs to be considered to express exposures as a percentage of AUM.