It's has less color, but still contains some of the olive's fruitiness. The remaining oil is the standard olive oil. Pale in color, this oil has only a hint of olive flavor. Other companies blend the different types or oil to help achieve a more standardized olive flavor. You mention a concern about rancidity.
Any oil can go rancid if stored in the wrong way.
Rancidity occurs when the oil reacts with oxygen forming substances that have a noticeably unpleasant smell and taste. Aside from its off-taste, the consumption of oxidized oil can also represents a health risk. The higher the proportion of unsaturated fatty acids, the greater the tendency for an oil to oxidize. This means that monounsaturated oils, such as olive oil, are more resistant to oxidative damage than polyunsaturated oils. It is heat and exposure to sun and air that encourage this type of breakdown, so store your oil in a well sealed bottle away from sun and heat.