The financing balance of the two cities increased by 458 million yuan.

[financing balance of the two cities increased by 458 million yuan] as of May 10, the financing balance of the Shanghai Stock Exchange was 801.598 billion yuan, an increase of 1.428 billion yuan over the previous trading day; the financing balance of the Shenzhen Stock Exchange was 726.527 billion yuan, a decrease of 970 million yuan over the previous trading day; the two cities totaled 1,528.125 billion yuan, an increase of 458 million yuan over the previous trading day.