Complex Capital Structure
The use of different forms of securities rather than relying solely on one class of common stock. A company with a complex capital structure might have a combination of several different varieties of common stock classes, with each class carrying different voting privileges and dividend rates. For example, a company with a complex capital structure might use both Class A and Class B common stock and preferred stock, as well as both callable bonds and non-callable bonds.
Taobiz explains Complex Capital Structure
Many companies issue different classes of stock in order to attract a wider variety of investors. In addition, the diversification of common stock types allows the company to approach market conditions with more flexibility.