Ella 
In early trading in Asia on Wednesday, GBP/USD rebounded near the key short-term support line and rebounded to 1.2570.
Amid broad dollar strength, GBP/USD fell to its lowest levels since June 13 before a two-and-a-half-month descending trendline combined with a downward oscillator triggered a rebound in GBP/USD. However, cautious market sentiment attracted GBP traders ahead of the release of the US August ISM Services Purchasing Managers Index (expected 52.6, previous value 52.7) and the US August S&P Global Purchasing Managers Index (S&P Global PMIs) final value.
In other news: ISM Services PMI Preview: Upbeat data could spook markets, boost dollar
GBP/USD is likely to move higher after bouncing off the key support line mentioned above, with muted MACD signals and the Relative Strength Index (14) below 50.0.
However, the confluence of the 100-day exponential moving average (EMA) and the 38.2% Fibonacci retracement of the March-July uptrend (near 1.2630) will act as upside resistance for GBP/USD.
After that, the descending resistance line from late July (around the 1.2700 round figure) will become the last line of defense for GBP/USD bears.
Additionally, the downtrend support line from late June (around 1.2530 at press time) will form support, followed by 200-index moving average support at 1.2490.
If the pound continues to be bearish after falling below 1.2490, the possibility of GBP/USD falling to around the 61.8% Fibonacci level of 1.2315 cannot be ruled out.
