By Dave Sebastian 



  Charles Schwab Corp. said its client assets were $4.49 trillion as of the end of August, up 21% from the year-ago period and 5% from July. 


  "Thus far in the third quarter, equity market returns have been quite strong and client trading activity very robust relative to prior years," Financial Chief Peter Crawford said. "At the same time, continued compression of interest rates has been pressuring investment yields." 


  Mr. Crawford said third-quarter revenue is running slightly lower than second-quarter results. The sharp reduction in long-term rates led to an acceleration in prepayment activity in mortgage-backed securities held in Schwab's portfolio, he said. 


  Core new assets brought by new and existing clients totaled $20 billion in August, the company said. Client cash was 12.5% of assets as of the end of August, compared with 11.3% in the same month last year and 13% in July. 


  Write to Dave Sebastian at dave.sebastian@wsj.com