MUFJ is >20% shareholder of Morgan Stanley, the counterpart to...

MUFJ is >20% shareholder of Morgan Stanley, the counterpart to the Equity swap with Athos Capital. As >20% shareholder, it is deemed to have influence over MS, so it declares as its own any position held by MS.
Athos has a contract to receive price performance of the stock from Morgan Stanley (Athos pays when stock declines). Athos probably has to have a collateral account with MS to do this. Essentially, Athos is making a leveraged bet on ADX, little cash up front, but all the economics net of financing costs.

In any case, MS declared ownership, but actually has no risk in holding the shares, other than counterparty risk (Athos not coming up with cash when shares fall).