Sentence:  Christiana Securities Company and Delaware Realty + Investment Company , major stockholders in du Pont , and the stockholders of Delaware were dealt with specially by provisions requiring the annual sale by a trustee , again over a ten <WSD>year</WSD> period , of du Pont 's General Motors stock allocable to them , as well as any General Motors stock which Christiana and Delaware owned outright . 
Meaning of the word marked with <WSD> tags:  a period of time containing 365 (or 366) days