The decision to invest arises from the need or interest in making an investment. The latter requires the investor to take strategic decisions that commit the project for long periods by mobilising considerable resources irreversibly. This means that when an investment is made by a ‘project owner’, it now renounces resources that, when invested in a project, are expected to generate future gains. In this context, an investment will only be undertaken if the expectation of future gains is higher than the initial investment. Given the uncertainty surrounding future flows and the high number of risks and obstacles involved in starting a new activity, it is strongly recommended to carry out a financial assessment of investment projects. This is of great importance as it helps inform decision-makers about the prospects of financial profitability. Unfortunately, many beginners neglect it, with regrettable consequences such as discontinuing operations or filing for bankruptcy, for example. However, various studies on entrepreneurship show that a well-prepared entrepreneur will be more likely to succeed than an improvised entrepreneur. In short, good preparation can avoid many errors and reduce contingencies. For this, there are a number of criteria that can help the decision-maker to choose. These methods include net present value, internal rate of return, payback time, etc. These methods are not miracle remedies and should be usefully integrated into the overall project strategy. What is more, the successful outcome of any investment project must always be understood as the result of a ‘constructed’ situation in relation to a reference situation, since it depends on a number of factors including, in particular, the investor’s motivations and objectives, the sector of activity of the project, the environment in which the project forms part, etc. In addition to the productive investment project, it may be necessary to invest in a financial asset (shares, bonds, derivative contracts, etc.). Indeed, economic developments in recent years have contributed significantly to the development and popularity of financial markets and a number of investors (individuals, institutions, governments) make extensive use of them for investing savings and hedging risks. A rational investor must choose the minimum risk portfolio for an expected level of return. This choice is linked to the concept of diversification, which is simply for an investor not to invest all in a single security, but to spread its investments over several securities, which allows it to achieve a better return/risk ratio. The measurement model for financial assets provides an estimate of the theoretical value of a financial asset.