Why is buyer the same as seller?

[Longhair]

TSE BLOCKS
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00:00 EDT Thursday, May 02, 2002

(Trades of 100,000 or more shares worth at least $1-million)
Stock Sym Buyer Seller Volume('000s) Price

Nortel Netwk NT Natl Bank Natl Bank 225 5.17
Nortel Netwk NT Natl Bank Natl Bank 225 5.19
Nortel Netwk NT NesBurns NesBurns 617 5.11