Difference between cum/cum and cum/ex:
http://www.manager-magazin.de/finanzen/artikel/cum-cum-steue...Is a Bloomberg link valid enough?
http://www.bloomberg.com/news/articles/2016-05-07/commerzban...Just search for Commerzbank on EN pages, plenty to choose from.
Another report by Reuters:
"The Handelsblatt story comes only days after media allegations that banks were using a different tax avoidance scheme called 'cum cum' sparked government criticism."
http://www.reuters.com/article/us-commerzbank-taxes-idUSKCN0..."Those deals, known as 'cum/ex' trades, were outlawed by Germany in 2012. Regulators are now moving to claw back the refunds from German banks. But the law didn’t address deals like Vanguard’s loan of Adidas shares, called 'cum/cum.'"
https://www.washingtonpost.com/business/economy/the-wall-str...Both seem to be subsets of div-arb (dividend-arbitrage) trading.
Second Orla's comment: Little to be gained from calling them something other than cum/cum.