Primary earnings per share (EPS) is a key financial metric that is closely monitored by investors and analysts. It is used to determine a company's profitability on a per-share basis. Synonyms for primary EPS include basic EPS, diluted EPS, headline EPS, and fully diluted EPS. Basic EPS is the simplest form of EPS, calculated by dividing a company's net income by its outstanding shares. Diluted EPS takes into account the potential dilution of outstanding shares through the conversion of convertible securities, such as stock options and warrants. Headline EPS refers to a company's EPS calculated using its reported earnings, while fully diluted EPS factors in all dilutive securities, including convertible debt.