Following the first full-talkie "Lights of New York", the low apparent influence (using this method) of Warner's part-talkie 1928 "Singing Fool" overlooks that

Following the first full-talkie "Lights of New York", the low apparent influence (using this method) of Warner's part-talkie 1928 "Singing Fool" overlooks that it starred Al Jolson, included several songs which became traditional, and made $4 million. Most studios moved to talkies within a year. I'd guess that analyzing the stockmarket is easier than the endless contingencies driving WP.