I bought a stock today and it struck my target price and I plan to sell it tomorrow, am I able to do so as there is a thing called T+2, will I be fined or is it illegal to do so?

Hi anon,

You won't be fined. This is called contra trading.

Even if you short and don't buy back on the same day, your broker might still be able to lend you shares to cover your position (of course while charging you a day's worth of interest). This is still preferrable to having SGX fine you.

You can even sell on the same day you bought! It is legal.

Only illegal if you short sell a stock and do not buy back on the same day.