(Adds London Stock Exchange)
July 31 (Reuters) - The following bids, mergers, acquisitions and disposals were reported by 2000 GMT on Wednesday:
**Some trading and investment firms are calling for competition regulators to scrutinise London Stock Exchange's LSE.L proposed $27 billion takeover of financial information provider Refinitiv to prevent further market data price hikes.
** EssilorLuxottica is buying Dutch opticians group GrandVision for up to 7.2 billion euros ($8 billion) in cash to take control of thousands of stores where it sells spectacles and lenses.
** Roche and Spark Therapeutics announced another extension of the Swiss drugmaker's $4.3 billion takeover offer for the U.S. gene therapy specialist as regulatory reviews in the United States and Britain continue.
** Resolute Mining Ltd said it would buy West Africa-focused Toro Gold Ltd in a cash and stock deal worth $274 million, as the company looks to expand production amid a run of consolidation in the gold industry.
** Oil firm DNO is casting an eye over Exxon Mobil's Norwegian assets as it looks for more deals after buying London-based peer Faroe earlier this year, its executive chairman said.
** Marijuana producer CannTrust Holdings Inc said it was exploring a possible sale, days after it fired its top boss following an investigation by Health Canada that showed the company grew cannabis in unlicensed rooms.
** Italian holding company CIR's healthcare unit KOS has signed an agreement to buy 100% of German nursing home company Charleston for 90 million euros ($100 million), CIR said.
Compiled by Manas Mishra and Arunima Kumar in Bengaluru