The increase of the company's value and, implicitly, value creation for shareholders are attainable objectives also because of the good management of the couple effectiveness - risk of investment projects. The company develops healthily if it promotes efficient investment projects, of which it obtains considerable cash flows, and which generate time value for the shareholders as a result of choosing the best combination of financing sources. This paper approaches statistical-mathematical models know in specialized literature in order to quantify the risk associated with investment projects in an uncertain environment. Unlike classical criteria of evaluating the efficiency of investments, based on the hypothesis of the irreversibility of the investment decision, the statistical-mathematical approaches do not ignore the flexible character of many investment initiatives.