The stock (also capital stock) of a corporation is all of the shares into which ownership of the corporation is divided. In American English, the shares are commonly known as "stocks". A single share of the stock represents fractional ownership of the corporation in proportion to the total number of shares.
Muslim should not facilitate unlawful business in any way. Unlawful business include usury, alcohol, pork, non Halal food, gambling, and any business which is forbidden in Islam. The platform which you want to create should not help people to do or invest or take part in unlawful business.
If the company is dealing with Halal products only and the finances were taken from non Muslim banks or financial institutions, then it is allowed to invest in its stocks.
Yes it is allowed as far as the company which issued the shares is dealing with fully lawful business.
It is allowed if the hotel group does not allow or deal with Haraam business like alcohol, singing parties, etc.
Yes it is permissible to buy and sell stocks in the stock market in any country as far as the company is not dealing in unlawful business like alcohol, pork, usury, weapons for harming people, gambling, production of sinful materials, etc.
Shares of any company involved in unlawful activity is unlawful to deal with.
If they close down with out any plans to restart alcohol business somewhere else, then helping them to sell stocks not linked with alcohol is allowed.
If they want to do the same unlawful business again, then it is not permissible to help them in any way.
In any case, helping in selling any material which can be used in alcohol is absolutely forbidden.
It is allowed to invest in stocks, bonds, mutual funds , cryptocurrancy . etc, but it is not allowed to invest in any share of a company which does unlawful investment or work, like alcohol, un Islamic banks, etc