June 3 (Reuters) - Hot Topic Inc (HOTT.O) posted a worse-than-expected 6.4 percent drop in May sales at stores open at least a year, hurt by lower transactions and a fall in average transaction amount, sending the mall and web-based retailer's shares down 8 percent.

An outfit by Jessica Louise, designer of a range for Hot Topic

Analysts had expected sames-store sales to fall 4.3 percent, according to Thomson Reuters Estimates.

Comparable-store sales declined 6.3 percent at the Hot Topic stores and 6.9 percent at Torrid stores.

Same-store sales at the men's category fell 8 percent, while that at the women's category declined 22 percent.

Virtually all accessory classifications slowed substantially from the first-quarter same-store sales trend as a result of lower levels of in-store traffic, CFO Jim McGinty said on a pre-recorded call.

Total net sales for the month rose 4 percent to $221.2 million.

The company, which also sells music and often hosts live bands at its stores, also said the three major music releases in May did not generate incremental sales nor did they drive overall traffic.

Shares of Hot Topic, known for its Goth- and rock 'n' roll-inspired apparel and accessories, were trading at $6.96 after the bell. They closed at $7.54 Wednesday 3 June on Nasdaq. (Reporting by Amitha Rajan in Bangalore; Editing by Deepak Kannan)