They are using their shares as collateral. Maybe into a prime...

They are using their shares as collateral. Maybe into a prime lender who loans to hedge funds.
So, outside of buying and selling, when shares are received the lender has given them back to Norges thereby raising Norges beneficial interest. Alternatively when they return the shares they are being lent out again, dropping Norges interest. So for Norges it's a journal entry, they are not trading the shares themselves. The problem is their holding is on the cusp of 5% therefore these things flip them over or under "substantial".