2 of 4 question amended

Die Gegenstand?

I am a beginner in German and this is my first post. I encounter the following sentence in a German article:

In vielen Fällen ... diese Eigenschaft ... , die Gegenstand dieses Kapitels ist.

I can not understand the use of "die" in front of "Gegenstand"(subject, topic, theme, etc.). According to the online dictionary, "Gegenstand" is masculine, and the only two cases of a leading "die" are: nominative plural and accusative plural, where the word should be "Gegenstände".

Is "die Gegenstand" grammatically correct ?