(Adds UBI Banca, Aareal Bank, Watford Holdings)
May 19 (Reuters) - The following bids, mergers, acquisitions and disposals were reported by 2000 GMT on Tuesday:
** UBI Banca has told Italy's market regulator Consob that a proposed takeover offer by bigger rival Intesa Sanpaolo should no longer be considered as valid, the country's fifth-largest bank said.
** German real estate lender Aareal Bank said it was inviting bids from financial investors for a significant minority stake in its Aareon unit to help finance the software business's future growth.
** Investment firm Capital Returns Management asked Watford Holdings Ltd to hire an investment bank and consider selling itself as the reinsurer's stock has lost more than half of its value since January and lags its peers.
** South Korea's KB Kookmin Bank plans to take a controlling stake in Bank Bukopin, Indonesia's Financial Services Authority (OJK) said in a statement, noting the mid-sized lender needed to strengthen its capital and liquidity.
** Exchange operator Cboe Global Markets said it is buying Canada's largest "dark pool" stock trading platform, MATCHNow, from Virtu Financial for an undisclosed amount to expand its geographical footprint.
** Germany and the Netherlands signed an agreement on to strengthen cooperation on electricity grids and look into different options, including Berlin taking a stake in Dutch state-owned power transmission grid operator TenneT.
** Energean Oil & Gas said it seeks to renegotiate its acquisition of Edison's upstream portfolio after its plan to immediately sell Edison's North Sea assets to Neptune Energy fell through.
** Thyssenkrupp could sell most of its steelmaking division, its CEO said, marking a historic reversal in strategy for the German conglomerate which has built its 200-year-old legacy as an industrial champion of the business.
** Sony Corp said it will turn its listed financial arm, Sony Financial Holdings Inc, into a wholly owned unit through a tender offer worth about 400 billion yen ($3.72 billion).
** Israeli defence firm Elbit Systems said the Charlesbank Technology Opportunities Fund invested $70 million in Elbit's commercial cybersecurity subsidiary Cyberbit.
** New Zealand media firm NZME Ltd withdrew its application to the country's Commerce Commission to allow it to buy major competitor Stuff.
** Dutch bank NIBC Holding NV said late on Monday it has agreed to pay its 2019 dividend to its proposed buyer, U.S. equity firm Blackstone Group Inc, before the deal settles, in order to remove one hurdle to the proposed 1.36 billion-euro ($1.47 billion) takeover. (Compiled by Shanti S Nair and C Nivedita in Bengaluru)