reading it as 'Maliki yawmi al-din' with a kasra (vowel sign i) on the kaf (letter k). According to this reading, the interpretation is: Its owner who possesses it.
Some of the reciters read it as 'Malika' with a fatha (vowel sign a) on the kaf, treating it as an invocation (nida'): O Master of the Day of Judgment.