31.   That helped pull the benchmark up as traders sold futures and bought the underlying cash index, a practice known as arbitrage.

32.   That helped pull up the underlying benchmark Nikkei as arbitrageurs then sold the futures and bought the underlying basket of stocks.

33.   That led securities firms to sell bond futures to hedge against such declines, said Yasunari Ueno, chief market economist at Fuji Securities Co.

34.   That in turn helped pull up the underlying benchmark Nikkei as arbitrageurs then sold the futures and bought the underlying basket of stocks.

35.   Surging stocks caused traders to sell bond futures earlier.

36.   The bank, which Makabe declined to identify, also sold money market futures to make the same bet, he said.

37.   The climb in futures helped pull up the benchmark index as traders sold futures and bought the underlying basket of stocks, a practice known as arbitrage.

38.   The rise in futures helped pull up the underlying index as arbitrageurs sold futures and bought cash to profit on the spread.

39.   This spring, for example, Chase sold its futures trading unit and said it would sell its stake in a Hong Kong credit-card company.

40.   Traders then sold futures and bought the underlying basket of stocks, a practice known as arbitrage.