In his answer to your question Dr. Monzer Kahf, Scholar in Islamic Economics & Financial Expert, stated,

It really depends on the market. This relaxation and tolerance is relative to the market one is investing in. In some markets there is sufficient number of Shari’ah abiding companies to the extent that an investor does not need any relaxation. But in some others, you may need a high level of it.
I cannot tell about any company in specific because I am not an investment advisor. I can only identify the shari’ah criteria and these basically are the main line of business and then seeing the numbers that the amount of Haram makes a relatively small percentage of the total company. In other words, as a Muslim you will need to study the numbers in this company: percentage of Haram income to total income, percentage of Haram sources of funds (e.g., depending on interest loans) to total sources of funds and percentage of usage of funds too. Based on these figures one may make a judgment.
Finally, What of if the investor asks the company to use his money only in the legitimate part of the business? No he cannot make that by his own intention because a company cannot be dissected.

May Allah guide all of us to what pleases Him!