Options traders in the iShares 20+Year Treasury Bond ETF (TLT) have been buying bullish calls throughout the summer, with the trend continuing on Tuesday. Data from ThinkOrSwim shows that traders bought more than 175,000 calls in the fund during the session, compared to just under 40,000 puts. This comes as long-duration bonds have borne the brunt of a nearly year-long rise in yields. The TLT fund itself rose 0.9% to $83.30 on Tuesday, its highest level since July 29.