Customers look at a Tesla Model S 90D electric vehicle at the company's showroom in Hanam, South Korea.

The new capital raised by Tesla may not be enough to alleviate ongoing investor concerns about its cash burn, said UBS, which has a sell rating on the company.

Tesla announced Wednesday that it is looking to raise $1.15 billion before the release of its mass-market Model 3 later this year.

"This is at the low end of the $1-2bn we expected, and could imply another raise later if the Model 3 is delayed," said UBS analyst Colin Langan in a note Thursday.